is the rate of change of velocity. It is measured in meter per second square (m/s2. Acceleration commonly is used for an increase of speed and a decrease in speed is called deceleration. Some objects with low densities do not accelerate as rapidly due to buoyancy and air resistance. In a vacuum all small objects have the same acceleration regardless of density.
TOPIC: Amplitude Modulation (AM) : When the amplitude of high frequency carrier wave is changed in accordance with the intensity of the signal, it is called amplitude modulation (AM).
is a traveling wave which is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations
sound is used by many species for detecting danger, navigation, predation, and communication. Earth's atmosphere, water, and virtually any physical phenomenon, such as fire, rain, wind, surf, or earthquake, produces (and is characterized by) its unique sounds.
The matter that supports the sound is called the medium.
The tendency of a body to resist any change in its motion (speed or direction) – in other words, to resist any change in its acceleration – is called its ‘inertia’. Mass can be thought of as a measure of a body’s inertia.
Inertia means ‘reluctance to change’. Inertia reduces a rate of change but cannot stop it. Inertia can take many forms, e.g.
• Electromagnets have electrical inertia: they resist changes of current through their coils.
• Flutes and organ pipes have acoustic inertia: their vibrations take time to diminish after the forces causing them stop.
You might help students develop a feeling for inertia by asking them:
• Can you stop a moving railway carriage that is smoothly running along a line, having just been shunted? Yes, but can you stop it easily, or at once?
• What keeps a spaceship going once it is far out in space, well away from the gravitational pull of the Earth and Sun, and the rocket motors are turned off? Is there anything to stop it moving? In both cases, inertia keeps the object moving. A force is needed to change its velocity, but even the smallest resultant (net) force will do so.
Masses of objects can be compared in principle by seeing how their velocity changes compare, in response to the same force or in the same interaction.
CHENEE NG TOPIC:NUCLEAR FISSION Nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts, often producing free neutrons and lighter nuclei, which may eventually produce photons (in the form of gamma rays). Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place). For fission to produce energy, the total binding energy of the resulting elements has to be higher than that of the starting element. Fission is a form of nuclear transmutation because the resulting fragments are not the same element as the original atom. Nuclear fission produces energy for nuclear power and to drive the explosion of nuclear weapons. Both uses are made possible because certain substances called nuclear fuels undergo fission when struck by free neutrons and in turn generate neutrons when they break apart. This makes possible a self-sustaining chain reaction that releases energy at a controlled rate in a nuclear reactor or at a very rapid uncontrolled rate in a nuclear weapon. The amount of free energy contained in nuclear fuel is millions of times the amount of free energy contained in a similar mass of chemical fuel such as gasoline, making nuclear fission a very tempting source of energy; however, the products of nuclear fission are radioactive and remain so for significant amounts of time, giving rise to a nuclear waste problem. Concerns over nuclear waste accumulation and over the destructive potential of nuclear weapons may counterbalance the desirable qualities of fission as an energy source, and give rise to ongoing political debate over nuclear power.
Isotopes are different types of atoms (nuclides) of the same chemical element, each having a different number of neutrons. Correspondingly, isotopes differ in mass number (or number of nucleons) but not in atomic number.[1] The number of protons (the atomic number) is the same because that is what characterizes a chemical element. For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14, respectively. The atomic number of carbon is 6, so the neutron numbers in these isotopes of carbon are therefore 12−6 = 6, 13−6 = 7, and 14–6 = 8, respectively. In short, isotope(s) of an element are different type of that element with different number of neutrons. It does not change the number of protons or electrons.
Isotopes are different types of atoms (nuclides) of the same chemical element, each having a different number of neutrons. Correspondingly, isotopes differ in mass number (or number of nucleons) but not in atomic number.[1] The number of protons (the atomic number) is the same because that is what characterizes a chemical element. For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14, respectively. The atomic number of carbon is 6, so the neutron numbers in these isotopes of carbon are therefore 12−6 = 6, 13−6 = 7, and 14–6 = 8, respectively. In short, isotope(s) of an element are different type of that element with different number of neutrons. It does not change the number of protons or electrons.
Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.
Almost everywhere, the shallow ground or upper 10 feet of the Earth's surface maintains a nearly constant temperature between 50° and 60°F (10° and 16°C). Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building. In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water. Geothermal Energy: The Earth's heat-called geothermal energy-escapes as steam at a hot springs in Nevada.
The Earth's heat-called geothermal energy-escapes as steam at a hot springs in Nevada. Credit: Sierra Pacific
In the United States, most geothermal reservoirs of hot water are located in the western states, Alaska, and Hawaii. Wells can be drilled into underground reservoirs for the generation of electricity. Some geothermal power plants use the steam from a reservoir to power a turbine/generator, while others use the hot water to boil a working fluid that vaporizes and then turns a turbine. Hot water near the surface of Earth can be used directly for heat. Direct-use applications include heating buildings, growing plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as pasteurizing milk.
Hot dry rock resources occur at depths of 3 to 5 miles everywhere beneath the Earth's surface and at lesser depths in certain areas. Access to these resources involves injecting cold water down one well, circulating it through hot fractured rock, and drawing off the heated water from another well. Currently, there are no commercial applications of this technology. Existing technology also does not yet allow recovery of heat directly from magma, the very deep and most powerful resource of geothermal energy.
Diffraction refers to various phenomena which occur when a wave encounters an obstacle. It is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings. Similar effects are observed when light waves travel through a medium with a varying refractive index or a sound wave through one with varying acoustic impedance. Diffraction occurs with all waves, including sound waves, water waves, and electromagnetic waves such as visible light, x-rays and radio waves. As physical objects have wave-like properties (at the atomic level), diffraction also occurs with matter and can be studied according to the principles of quantum mechanics.
While diffraction occurs whenever propagating waves encounter such changes, its effects are generally most pronounced for waves where the wavelength is on the order of the size of the diffracting objects. If the obstructing object provides multiple, closely-spaced openings, a complex pattern of varying intensity can result. This is due to the superposition, or interference, of different parts of a wave that traveled to the observer by different paths (see diffraction grating).
The formalism of diffraction can also describe the way in which waves of finite extent propagate in free space. For example, the expanding profile of a laser beam, the beam shape of a radar antenna and the field of view of an ultrasonic transducer are all explained by diffraction theory.
Diffusion is a time-dependent process, constituted by random motion of given entities and causing the statistical distribution of these entities to spread in space. The concept of diffusion is tied to notion of mass transfer, driven by a concentration gradient.
The concept of diffusion emerged in the physical sciences. The paradigmatic examples were heat diffusion, molecular diffusion and Brownian motion. Their mathematical description was elaborated by Joseph Fourier in 1822, Adolf Fick in 1855 and by Albert Einstein in 1905.
Applications outside physics were pioneered by Louis Bachelier who in 1900 used a random walk model to describe price fluctuations on financial markets. In a less quantitative way, the concept of diffusion is invoked in the social sciences to describe the spread of ideas (Diffusion of innovations, Lexical diffusion, Trans-cultural diffusion).
Other types of diffusion
* Atomic diffusion, in solids. * Eddy diffusion, incoarse-grained description of turbulent flow * Effusion of a gas through small holes. * Electronic diffusion, resulting in an electric current called the diffusion current. * Facilitated diffusion, present in some organisms. * Gaseous diffusion, used for isotope separation * Heat equation, diffusion of thermal energy * Itō diffusion, mathematisation of Brownian motion, continuous stochastic process. * Knudsen diffusion of gas in long pores with frequent wall collisions * Momentum diffusion, ex. the diffusion of the hydrodynamic velocity field * Osmosis is the diffusion of water through a cell membrane. * Photon diffusion * Reverse diffusion, against the concentration gradient, in phase separation * Rotational diffusion, random reorientions of molecules * Surface diffusion, diffusion of adparticles on a surface
bouyancy means tendency of an object immersed in a fluid to float. boats float in water in balloons float in air due to bouyancy everything pretty much nash bouyant forces the battle ship arizona on the bottom of pearl harbor wont float but bouyant force make it lighter.you weigt less because of the bouyant force on air.
acceleration is the change in velocity over time.[1] Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, i.e. a line, acceleration is the rate at which something speeds up or slows down. However, as a vector quantity, acceleration is also the rate at which direction changes.[2][3] Acceleration has the dimensions L T−2. In SI units, acceleration is measured in metres per second squared (m/s2).
In common speech, the term acceleration commonly is used for an increase in speed (the magnitude of velocity); a decrease in speed is called deceleration. In physics, a change in the direction of velocity also is an acceleration: for rotary motion, the change in direction of velocity results in centripetal (toward the center) acceleration; where as the rate of change of speed is a tangential acceleration.
In classical mechanics, for a body with constant mass, the acceleration of the body is proportional to the resultant (total) force acting on it (Newton's second law):
A quark is one of the fundamental particles in physics. They join together to form hadrons, such as protons and neutrons. The study of quarks and the interactions between them is called quantum chromodynamics.
The anti-particle of a quark is the antiquark. Quarks and antiquarks are the only two fundamental particles that interact through all four fundamental forces of physics.
A quark exhibits confinement, which means that the quarks are not observed independently but always in combination with other quarks. This makes determining the properties (mass, spin, and parity) impossible to measure directly; these traits must be inferred from the particles composed of them.
These measurements indicate a non-integer spin (either +1/2 or -1/2), so quarks are fermions and follow the Pauli Exclusion Principle. There are 6 flavours of quarks: up, down, strange, charm, bottom, and top.
The flavour of the quark determines its properties. Quarks with a charge of +(2/3)e are called up-type quarks and those with a charge of -(1/3)e are called down-type. There are three generations of quarks, based on pairs of weak positive/negative weak isospin. The first generation are up & down quarks, the second generation are strange & charm quarks, the third generation are top & bottom quarks.
All quarks have a baryon number (B = 1/3) and a lepton number (L = 0). The flavour determines certain other unique properties, described in individual descriptions. (See links to the right.)
A transistor is a semiconductor device used to amplify or switch electronic signals. It is made of a solid piece of semiconductor material, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing through another pair of terminals. Because the controlled (output) power can be much more than the controlling (input) power, the transistor provides amplification of a signal. Some transistors are packaged individually but many more are found embedded in integrated circuits.
Transistor as an amplifier Amplifier circuit, standard common-emitter configuration.
The common-emitter amplifier is designed so that a small change in voltage in (Vin) changes the small current through the base of the transistor and the transistor's current amplification combined with the properties of the circuit mean that small swings in Vin produce large changes in Vout.
It is important that the operating values of the transistor are chosen and the circuit designed such that as far as possible the transistor operates within a linear portion of the graph, such as that shown between A and B, otherwise the output signal will suffer distortion.
Various configurations of single transistor amplifier are possible, with some providing current gain, some voltage gain, and some both.
From mobile phones to televisions, vast numbers of products include amplifiers for sound reproduction, radio transmission, and signal processing. The first discrete transistor audio amplifiers barely supplied a few hundred milliwatts, but power and audio fidelity gradually increased as better transistors became available and amplifier architecture evolved.
Modern transistor audio amplifiers of up to a few hundred watts are common and relatively inexpensive.
Some musical instrument amplifier manufacturers mix transistors and vacuum tubes in the same circuit, as some believe tubes have a distinctive sound.
TOPIC:Phosphorus Phosphorus (pronounced /ˈfɒsfərəs/, FOS-fər-əs) is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks. Elemental phosphorus exists in two major forms - white phosphorus and red phosphorus. Although the term "phosphorescence", meaning glow after illumination, derives from phosphorus, glow of phosphorus originates from oxidation of the white (but not red) phosphorus and should be called chemiluminescence.
Due to its high reactivity, phosphorus is never found as a free element in nature on Earth. The first form of phosphorus to be discovered (white phosphorus, in 1669) emits a faint glow upon exposure to oxygen — hence its name given from Greek mythology, Φωσφόρος meaning "light-bearer" (Latin Lucifer), referring to the "Morning Star", the planet Venus.
Phosphorus is a component of DNA, RNA, ATP, and also the phospholipids which form all cell membranes. It is thus an essential element for all living cells. The most important commercial use of phosphorus-based chemicals is the production of fertilizers.
Phosphorus compounds are also widely used in explosives, nerve agents, friction matches, fireworks, pesticides, toothpaste and detergents.
Projectile motion refers to the motion of an object projected into the air at an angle. A few examples of this include a soccer ball begin kicked, a baseball begin thrown, or an athlete long jumping. Even fireworks and water fountains are examples of projectile motion. In this lesson you will learn the fundamentals of projectile motion. You will be given examples and interesting facts. Finally, you will get to test your knowledge with a game called Water Balloons!.
A diaphragm is a thin rubber dome with a springy and flexible rim. It is inserted into the vagina, fits over the cervix and is held in place by vaginal muscles. A diaphragm holds spermicide in place over the cervix (opening to the uterus). Spermicide kills sperm, preventing fertilization. After intercourse, it should be left in place for 6-8 hours. Diaphragms are 86-94% effective as birth control.
Diaphragms may offer some limited protection against reproductive tract infections and HIV/AIDS. See Cervical Barriers Advancement Society for the latest information.
Use
Getting a diaphragm requires a fitting in a clinic. During the fitting, a fitting ring is inserted into the vagina. The largest ring that fits comfortably is usually the one chosen. Different types of diaphragms are available. You and your medical provider can decide between coil, flat, or arcing spring diaphragms.
Diaphragms can be inserted up to 2 hours before sex because spermicide is only effective for 2 hours. If you insert your diaphragm more than 2 hours before intercourse, you will have to insert more spermicide into your vagina. To do this, leave your diaphragm in and use an applicator to add more spermicide directly into the vagina. Every time a woman has intercourse, she will need to add more spermicide to her vagina with an applicator.
Leslie Groves and J. Robert OppenheimerIn a national survey at the turn of the millennium, both journalists and the public ranked the dropping of the atomic bomb and the end of the Second World War as the top news stories of the twentieth-century. The advent of nuclear weapons, made possible by the Manhattan Project, not only helped bring an end to the Second World War -- it ushered in the atomic age and determined how the next war, the Cold War, would be fought.
The United States Department of Energy Office of History and Heritage Resources, with the assistance of a graduate fellow, has been developing an interactive web site on the Manhattan Project. When completed, The Manhattan Project: An Interactive History will total some 120,000 words and over 200 pages and 500 images, including photographs, maps, and drawings. The site is being implemented incrementally, with the "Events of the Manhattan Project" and "Resources Relating to the Manhattan Project" sections the first part to go online. Click on the Events or Resources buttons to the left for a listing of currently available pages.
The remaining sections are scheduled to go online in the near future. Click on the buttons to the left for listings of the projected web pages under each heading.
Lovely Guilleno Gamma decay There are three types of radiation the alpha decay, beta decay, and gamma decay I was focused in the gamma decay type of radiation. A gamma decay is a radioactive process in which an atomic nucleus loses energy by emitting a gamma ray without a change in its atomic or mass numbers. And it is a decay of an unstable elementary particle by photon emission.
and also it is a stream of high-energy photons. When an element undergoes gamma decay its atomic number and mass number do not change.
Displacement is the shifting of actions from a desired target to a substitute target when there is some reason why the first target is not permitted or not available.
Displacement may involve retaining the action and simply shifting the target of that action. Where this is not feasible, the action itself may also change. Where possible the second target will resemble the original target in some way.
Phobias may also use displacement as a mechanism for releasing energy that is caused in other ways. Example
The boss gets angry and shouts at me. I go home and shout at my wife. She then shouts at our son. With nobody left to displace anger onto, he goes and kicks the dog.
A man wins the lottery. He turns to the person next to him and gives the person a big kiss.
A boy is afraid of horses. It turns out to be a displaced fear of his father.
I want to speak at a meeting but cannot get a word in edgeways. Instead, I start scribbling furiously.
A religious person who is sexually frustrated focuses their attention on food, becoming a gourmet.
A woman, rejected by her boyfriend, goes out with another man 'on the rebound'. Discussion
Displacement occurs when the Id wants to do something of which the Super ego does not permit. The Ego thus finds some other way of releasing the psychic energy of the Id. Thus there is a transfer of energy from a repressed object-cathexis to a more acceptable object.
Displaced actions tend to be to into related areas or subjects. If I want to shout at a person but feel that I cannot, then shouting at somebody else is preferred to going to play the piano, although this may still be used if there is no other way I can release my anger.
Displacements are often quite satisfactory and workable mechanisms for releasing energy more safely.
The atom is a basic unit of matter consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons (except in the case of hydrogen-1, which is the only stable nuclide with no neutron). The electrons of an atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can remain bound to each other, forming a molecule. An atom containing an equal number of protons and electrons is electrically neutral, otherwise it has a positive or negative charge and is an ion. An atom is classified according to the number of protons and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determine the isotope of the element.[1]
The name atom comes from the Greek ἄτομος/átomos, α-τεμνω, which means uncuttable, or indivisible, something that cannot be divided further. The concept of an atom as an indivisible component of matter was first proposed by early Indian and Greek philosophers. In the 17th and 18th centuries, chemists provided a physical basis for this idea by showing that certain substances could not be further broken down by chemical methods. During the late 19th and early 20th centuries, physicists discovered subatomic components and structure inside the atom, thereby demonstrating that the 'atom' was divisible. The principles of quantum mechanics were used to successfully model the atom.[2][3]
Relative to everyday experience, atoms are minuscule objects with proportionately tiny masses. Atoms can only be observed individually using special instruments such as the scanning tunneling microscope. Over 99.9% of an atom's mass is concentrated in the nucleus,[note 1] with protons and neutrons having roughly equal mass. Each element has at least one isotope with unstable nuclei that can undergo radioactive decay. This can result in a transmutation that changes the number of protons or neutrons in a nucleus.[4] Electrons that are bound to atoms possess a set of stable energy levels, or orbitals, and can undergo transitions between them by absorbing or emitting photons that match the energy differences between the levels. The electrons determine the chemical properties of an element, and strongly influence an atom's magnetic properties
Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. In this case the energy extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head. To obtain very high head, water for a hydraulic turbine may be run through a large pipe called a penstock.[3]
Pumped storage hydroelectricity produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine. Pumped storage schemes currently provide the only commercially important means of large-scale grid energy storage and improve the daily capacity factor of the generation system. Hydroelectric plants with no reservoir capacity are called run-of-the-river plants, since it is not then possible to store water. A tidal power plant makes use of the daily rise and fall of water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot waterwheels.
junavil hangco HYDROELECTRICPOWER Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. In this case the energy extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head. To obtain very high head, water for a hydraulic turbine may be run through a large pipe called a penstock.[3]
Pumped storage hydroelectricity produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine. Pumped storage schemes currently provide the only commercially important means of large-scale grid energy storage and improve the daily capacity factor of the generation system. Hydroelectric plants with no reservoir capacity are called run-of-the-river plants, since it is not then possible to store water. A tidal power plant makes use of the daily rise and fall of water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot waterwheels.
Atmospheric pressure is defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Low pressure areas have less atmospheric mass above their location, whereas high pressure areas have more atmospheric mass above their location. Similarly, as elevation increases there is less overlying atmospheric mass, so that pressure decreases with increasing elevation. A column of air one square inch in cross-section, measured from sea level to the top of the atmosphere, would weigh approximately 14.7 lbf (65 N). The standard atmosphere (symbol: atm) is a unit of pressure and is defined as being equal to 101,325 Pa or 101.325 kPa. [1][2] The following units are equivalent, but only to the number of decimal places displayed: 760 mmHg (torr), 29.92 inHg, 14.696 PSI, 1013.25 millibars. One standard atmosphere is standard pressure used for pneumatic fluid power (ISO R554), and in the aerospace (ISO 2533) and petroleum (ISO 5024) industries.
In classical mechanics, momentum (pl. momenta; SI unit kg·m/s, or, equivalently, N·s) is the product of the mass and velocity of an object (p = mv). For more accurate measures of momentum, see the section "modern definitions of momentum" on this page. It is sometimes referred to as linear momentum to distinguish it from the related subject of angular momentum. Linear momentum is a vector quantity, since it has a direction as well as a magnitude. Angular momentum is a pseudovector quantity because it gains an additional sign flip under an improper rotation. The total momentum of any group of objects remains the same unless outside forces act on the objects (law of conservation of momentum).
Momentum is a conserved quantity, meaning that the total momentum of any closed system (one not affected by external forces) cannot change. Although originally seen to be due to Newton's laws, this law is also true in special relativity, and with appropriate definitions a (generalized) momentum conservation law holds in electrodynamics, quantum mechanics, quantum field theory, and general relativity.
-it is the change in direction of a wave due to a change in its speed. This is most commonly observed when a wave passes from one medium to another at an angle. Refraction of light is the most commonly observed phenomenon, but any type of wave can refract when it interacts with a medium, for example when sound waves pass from one medium into another or when water waves move into water of a different depth. Refraction is described by Snell's law, which states that the angle of incidence θ1 is related to the angle of refraction θ2 by
where v1 and v2 are the wave velocities in the respective media, and n1 and n2 the refractive indices. In general, the incident wave is partially refracted and partially reflected; the details of this behavior are described by the Fresnel equations.
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The law of reflection says that for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected. Mirrors exhibit specular reflection.
Laws of regular reflection
If the reflecting surface is very smooth, the reflection of light that occurs is called specular or regular reflection. The laws of reflection are as follows:
1. The incident ray, the reflected ray and the normal to the reflection surface at the point of the incidence lie in the same plane. 2. The angle which the incident ray makes with the normal is equal to the angle which the reflected ray makes to the same normal. 3. Light paths are reversible.
plant Any organism in the kingdom Plantae, consisting of multicellular, eukaryotic life forms (see eukaryote) with six fundamental characteristics: photosynthesis as the almost exclusive mode of nutrition, essentially unlimited growth at meristems, cells that contain cellulose in their walls and are therefore somewhat rigid, the absence of organs of movement, the absence of sensory and nervous systems, and life histories that show alternation of generations. No definition of the kingdom completely excludes all nonplant organisms or even includes all plants. Many plants, for example, are not green and thus do not produce their own food by photosynthesis, being instead parasitic on other living plants (see parasitism). Others obtain their food from dead organic matter. Many animals possess plantlike characteristics, such as a lack of mobility (e.g., sponges) or the presence of a plantlike growth form (e.g., some corals and bryozoans), but in general such animals lack other plant characteristics. Some past classification systems (see taxonomy) placed difficult groups such as protozoans, bacteria, algae, slime molds, and fungi (see fungus) in the plant kingdom, but structural and functional differences between these organisms and plants have convinced most scientists to classify them elsewhere.
Inertia is the name for the tendency of an object in motion to remain in motion, or an object at rest to remain at rest, unless acted upon by a force. This concept was quantified in Newton's First Law of Motion.
Inherent property of a body that makes it oppose any force that would cause a change in its motion. A body at rest and a body in motion both oppose forces that might cause acceleration. The inertia of a body can be measured by its mass, which governs its resistance to the action of a force, or by its moment of inertia about a specified axis, which measures its resistance to the action of a torque about the same axis.
According to Newton’s law of inertia, the tendency of a body that is at rest to remain at rest and a body that is in motion to continue in motion with constant speed in the same straight line unless acted on by an outside force.
Coulomb's law is a law of physics describing the electrostatic interaction between electrically charged particles. It was studied and first published in 1783 by French physicist Charles Augustin de Coulomb and was essential to the development of the theory of electromagnetism. Nevertheless, the dependence of the electric force with distance (inverse square law) had been proposed previously by Joseph Priestley[1] and the dependence with both distance and charge had been discovered, but not published, by Henry Cavendish, prior to Coulomb's works.
Coulomb's law may be stated in scalar form as follows:
The magnitude of the electrostatic force between two point electric charges is directly proportional to the product of the magnitudes of each of the charges and inversely proportional to the square of the distance between the two charges.
Sound is a travelling wave which is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.[1]
The mechanical vibrations that can be interpreted as sound are able to travel through all forms of matter: gases, liquids, solids, and plasmas. The matter that supports the sound is called the medium. Sound cannot travel through vacuum.
I will share to you about the speed of light The speed of light is a physical constant. Its value is exactly 299,792,458 metres per second,[1][2] often approximated as 300,000 kilometres per second or 186,000 miles per second (see the table on the right for values in other units). It is the speed of electromagnetic radiation (such as radio waves, visible light, or gamma rays) in vacuum, where there are no atoms, molecules or other types of matter that can slow it down.
For much of human history, it was not known whether light was transmitted instantaneously or simply very quickly. In the 17th century, Ole Rømer first demonstrated that it travelled at a finite speed by studying the apparent motion of Jupiter's moon Io. After centuries of increasingly precise measurements, in 1975 the speed of light was known to be 299,792,458 m/s with a relative measurement uncertainty of 4 parts per billion. In 1983, the metre was redefined in the International System of Units (SI) as the distance travelled by light in vacuum in 1⁄299,792,458 of a second. As a result, the numerical value of c in metres per second is now fixed exactly by the definition of the metre.
According to the theory of special relativity, c connects space and time in the unified structure of spacetime, and its square is the constant of proportionality between mass and energy (E = mc2) In any inertial frame of reference, independently of the relative velocity of the emitter and the observer, c is the speed of all massless particles and associated fields, including all electromagnetic radiation in free space,and it is believed to be the speed of gravity and of gravitational waves. It is an upper bound on the speed at which energy, matter, and information can travel, as surpassing it "would lead to the destruction of the essential relation between cause and effect.".Its finite value is a limiting factor in the speed of operation of electronic devices.
The actual speed at which light propagates through transparent materials, such as glass or air, is less than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c / v). For example, for visible light the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200,000 km/s; the refractive index of air for visible light is about 1.0003, so the speed of light in air is very close to c.
The speed of light (usually denoted c) is a physical constant. Its value is exactly 299,792,458 metres per second, often approximated as 300,000 kilometres per second or 186,000 miles per second (see the table on the right for values in other units). It is the speed of electromagnetic radiation (such as radio waves, visible light, or gamma rays) in vacuum, where there are no atoms, molecules or other types of matter that can slow it down.
For much of human history, it was not known whether light was transmitted instantaneously or simply very quickly. In the 17th century, Ole Rømer first demonstrated that it travelled at a finite speed by studying the apparent motion of Jupiter's moon Io. After centuries of increasingly precise measurements, in 1975 the speed of light was known to be 299,792,458 m/s with a relative measurement uncertainty of 4 parts per billion. In 1983, the metre was redefined in the International System of Units (SI) as the distance travelled by light in vacuum in 1⁄299,792,458 of a second. As a result, the numerical value of c in metres per second is now fixed exactly by the definition of the metre.
According to the theory of special relativity, c connects space and time in the unified structure of spacetime, and its square is the constant of proportionality between mass and energy (E = mc2). In any inertial frame of reference, independently of the relative velocity of the emitter and the observer, c is the speed of all massless particles and associated fields, including all electromagnetic radiation in free space, and it is believed to be the speed of gravity and of gravitational waves. It is an upper bound on the speed at which energy, matter, and information can travel, as surpassing it "would lead to the destruction of the essential relation between cause and effect." Its finite value is a limiting factor in the speed of operation of electronic devices.
The actual speed at which light propagates through transparent materials, such as glass or air, is less than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c / v). For example, for visible light the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200,000 km/s; the refractive index of air for visible light is about 1.0003, so the speed of light in air is very close to c.
Let us begin our explanation of how Newton changed our undestanding of the Universe by enumerating his Three Laws of Motion.
NEWTON'S FIRST LAW OF MOTION:
I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
=This we recognize as essentially Galileo's concept of inertia,and this is often termed simply the "LAW OF INERTIA".
NEWTON'S SECOND LAW OF MOTION:
II. The relations between an object's mass M,its acceleration A,and the appleied force F is F=ma. Acceleration and force are vectors (as indicated by their symblos being displayedin slant bold font);in this law the direction of the force vector is the same as the direction of the acceleration vector.
=This is the most powerful of Newtons three Laws,because it allows quantitative calculations o dynamics: how do velocities change when forces are applied. Notice the fundemental difference between Newton's Law and the dynamics of Aristotle: according to Newton,a force causes only a change in velocity (an acceleration); it does not maintain the velocity as Aristotle held.
This is sometimes summarized by saying that under Newton,F=ma,but under Aristotle F=mv,where v is the velocity. Thus,according to Aristotle there is only a velocity if there is force,but according to Newton an object with a certain velocity maintains that velocity unless a force acts on it to cause an acceleartion (that is,that is,a change in the velocity). As we have noted earlier in conjuction with discussion of Galelio,Aristotle's view seems to be more in accord with common sense,but that is because of a failure to appreciate the role played by frictional forces. Once account taken of all forces acting in a given situation it is the dynamics of Galelio and Newton,not of Aristotle,that are found to be in accord the observations.
NEWTON'S THIRD LAW OF MOTION:
III. For every action there is an equal and opposite reaction.
=This law is exemplified by what happens if we step off a boat onto the bank of a lake: as we move in the direction of the shore,the boat tends to move in the opposite direction (leaving us facedown in the water,if we aren't careful!).
When you talk about weight and forces you have to conclude that you are dealing with a falling body, and that other forces such as air resistance etc are ignored: Now your question: If a body is falling towards the earth it experiences a downward force equivalent to its weight: that is mass of the body multiplied by the acceleration due to gravity. Unbalanced or Resultant force on body = mass * acceleration. This is measured in N As an example, a 100kg man will have a downward force acting on him of 981N This force is in actual fact an unbalanced force acting downwards, and the acceleration will be 9.81m/s³
As far as I can determine, the only possible way that an unbalanced force equal to the weight of the man can affect the acceleration is if a further 981N force is applied downwards on the man. The total force acting downwards on the man will then be 1,962N, and his acceleration downwards will be 19.62m/s².
If a 981N force is applied upward on the man, he will stop falling, his velocity will be zero. But this is not an unbalanced force: It is a force exactly in equilibrium with the downward force on the man.
I have tried to answer this as best I can. Maybe I am missing some fundamental point. But I must admit that I do not really understand the wording of the question.
Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles emitted are a form of ionizing radiation also known as beta rays. The production of beta particles is termed beta decay. They are designated by the Greek letter beta (β). There are two forms of beta decay, β− and β+, which respectively give rise to the electron and the positron.
USES:
Beta particles can be used to treat health conditions such as eye and bone cancer, and are also used as tracers. Strontium-90 is the material most commonly used to produce beta particles. Beta particles are also used in quality control to test the thickness of an item, such as paper, coming through a system of rollers. Some of the beta radiation is absorbed while passing through the product. If the product is made too thick or thin, a correspondingly different amount of radiation will be absorbed. A computer program monitoring the quality of the manufactured paper will then move the rollers to change the thickness of the final product.
Inverse beta decay of a radioactive tracer isotope is the source of the positrons used in positron emission tomography (PET scan).
In electronics, a diode is a two-terminal electronic component that conducts electric current in only one direction. The term usually refers to a semiconductor diode, the most common type today, which is a crystal of semiconductor connected to two electrical terminals, a P-N junction. A vacuum tube diode, now little used, is a vacuum tube with two electrodes; a plate and a cathode.
The most common function of a diode is to allow an electric current in one direction (called the diode's forward direction) while blocking current in the opposite direction (the reverse direction). Thus, the diode can be thought of as an electronic version of a check valve. This unidirectional behavior is called rectification, and is used to convert alternating current to direct current, and remove modulation from radio signals in radio receivers.
However, diodes can have more complicated behavior than this simple on-off action, due to their complex non-linear electrical characteristics, which can be tailored by varying the construction of their P-N junction. These are exploited in special purpose diodes that perform many different functions. Diodes are used to regulate voltage (Zener diodes), electronically tune radio and TV receivers (varactor diodes), generate radio frequency oscillations (tunnel diodes), and produce light (light emitting diodes).
Diodes were the first semiconductor electronic devices. The discovery of crystals' rectifying abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's whisker diodes were made of crystals of minerals such as galena. Today most diodes are made of silicon, but other semiconductors such as germanium are sometimes used.
When you talk about weight and forces you have to conclude that you are dealing with a falling body, and that other forces such as air resistance etc are ignored: Now your question: If a body is falling towards the earth it experiences a downward force equivalent to its weight: that is mass of the body multiplied by the acceleration due to gravity. Unbalanced or Resultant force on body = mass * acceleration. This is measured in N As an example, a 100kg man will have a downward force acting on him of 981N This force is in actual fact an unbalanced force acting downwards, and the acceleration will be 9.81m/s³
As far as I can determine, the only possible way that an unbalanced force equal to the weight of the man can affect the acceleration is if a further 981N force is applied downwards on the man. The total force acting downwards on the man will then be 1,962N, and his acceleration downwards will be 19.62m/s².
If a 981N force is applied upward on the man, he will stop falling, his velocity will be zero. But this is not an unbalanced force: It is a force exactly in equilibrium with the downward force on the man.
I have tried to answer this as best I can. Maybe I am missing some fundamental point. But I must admit that I do not really understand the wording of the question.
In kinematics, the instantaneous speed of an object (denoted v) is the magnitude of its instantaneous velocity (the rate of change of its position); it is thus the scalar equivalent of velocity. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero.
Like velocity, speed has the dimensions of a length divided by a time; the SI unit of speed is the meter per second, but the most usual unit of speed in everyday usage is the kilometer per hour or, in certain countries, the mile per hour.
The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in vacuum c = 299,792,458 meters per second, approximately 1079 million kilometers (671 million miles) per hour. Matter cannot quite reach the speed of light, as this would require an infinite amount of energy.
A light ray is a stream of light with the smallest possible cross-sectional area. (Rays are theoretical constructs.) The incident ray is defined as a ray approaching a surface. The point of incidence is where the incident ray strikes a surface. The normal is a construction line drawn perpendicular to the surface at the point of incidence. The reflected ray is the portion of the incident ray that leaves the surface at the point of incidence. The angle of incidence is the angle between the incident ray and the normal. The angle of reflection is the angle between the normal and the reflected ray.
topic : Spin
ReplyDelete*spin direction
*spin vector
*spin projection
*spin operator
Jeremiah Arcinas
ReplyDeletetopic: Acceleration
is the rate of change of velocity. It is measured in meter per second square (m/s2. Acceleration commonly is used for an increase of speed and a decrease in speed is called deceleration. Some objects with low densities do not accelerate as rapidly due to buoyancy and air resistance. In a vacuum all small objects have the same acceleration regardless of density.
This comment has been removed by the author.
ReplyDeleteTOPIC: Amplitude Modulation (AM) : When the amplitude of high frequency carrier wave is changed in accordance with the intensity of the signal, it is called amplitude modulation (AM).
ReplyDeleteThis comment has been removed by the author.
ReplyDeletetopic:radiation
ReplyDeletedescribes any process in which energy emitted by one body travels through a medium or through space, ultimately to be absorbed by another body.
which can also be ionizing radiation, to acoustic radiation, or to other more obscure processes
radioactive decay.
*Alpha radiation(α)
*Beta(+/-) radiation(β-)
*Gamma radiation(γ)
topic sound:
ReplyDeleteis a traveling wave which is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations
sound is used by many species for detecting danger, navigation, predation, and communication. Earth's atmosphere, water, and virtually any physical phenomenon, such as fire, rain, wind, surf, or earthquake, produces (and is characterized by) its unique sounds.
The matter that supports the sound is called the medium.
Inertia
ReplyDeleteThe tendency of a body to resist any change in its motion (speed or direction) – in other words, to resist any change in its acceleration – is called its ‘inertia’. Mass can be thought of as a measure of a body’s inertia.
Inertia means ‘reluctance to change’. Inertia reduces a rate of change but cannot stop it. Inertia can take many forms, e.g.
• Electromagnets have electrical inertia: they resist changes of current through their coils.
• Flutes and organ pipes have acoustic inertia: their vibrations take time to diminish after the forces causing them stop.
You might help students develop a feeling for inertia by asking them:
• Can you stop a moving railway carriage that is smoothly running along a line, having just been shunted? Yes, but can you stop it easily, or at once?
• What keeps a spaceship going once it is far out in space, well away from the gravitational pull of the Earth and Sun, and the rocket motors are turned off? Is there anything to stop it moving?
In both cases, inertia keeps the object moving. A force is needed to change its velocity, but even the smallest resultant (net) force will do so.
Masses of objects can be compared in principle by seeing how their velocity changes compare, in response to the same force or in the same interaction.
CHENEE NG
ReplyDeleteTOPIC:NUCLEAR FISSION
Nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts, often producing free neutrons and lighter nuclei, which may eventually produce photons (in the form of gamma rays). Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place). For fission to produce energy, the total binding energy of the resulting elements has to be higher than that of the starting element. Fission is a form of nuclear transmutation because the resulting fragments are not the same element as the original atom.
Nuclear fission produces energy for nuclear power and to drive the explosion of nuclear weapons. Both uses are made possible because certain substances called nuclear fuels undergo fission when struck by free neutrons and in turn generate neutrons when they break apart. This makes possible a self-sustaining chain reaction that releases energy at a controlled rate in a nuclear reactor or at a very rapid uncontrolled rate in a nuclear weapon.
The amount of free energy contained in nuclear fuel is millions of times the amount of free energy contained in a similar mass of chemical fuel such as gasoline, making nuclear fission a very tempting source of energy; however, the products of nuclear fission are radioactive and remain so for significant amounts of time, giving rise to a nuclear waste problem. Concerns over nuclear waste accumulation and over the destructive potential of nuclear weapons may counterbalance the desirable qualities of fission as an energy source, and give rise to ongoing political debate over nuclear power.
Isotopes are different types of atoms (nuclides) of the same chemical element, each having a different number of neutrons. Correspondingly, isotopes differ in mass number (or number of nucleons) but not in atomic number.[1] The number of protons (the atomic number) is the same because that is what characterizes a chemical element. For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14, respectively. The atomic number of carbon is 6, so the neutron numbers in these isotopes of carbon are therefore 12−6 = 6, 13−6 = 7, and 14–6 = 8, respectively. In short, isotope(s) of an element are different type of that element with different number of neutrons. It does not change the number of protons or electrons.
ReplyDeleteIsotopes are different types of atoms (nuclides) of the same chemical element, each having a different number of neutrons. Correspondingly, isotopes differ in mass number (or number of nucleons) but not in atomic number.[1] The number of protons (the atomic number) is the same because that is what characterizes a chemical element. For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14, respectively. The atomic number of carbon is 6, so the neutron numbers in these isotopes of carbon are therefore 12−6 = 6, 13−6 = 7, and 14–6 = 8, respectively. In short, isotope(s) of an element are different type of that element with different number of neutrons. It does not change the number of protons or electrons.
ReplyDeleteGeothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.
ReplyDeleteAlmost everywhere, the shallow ground or upper 10 feet of the Earth's surface maintains a nearly constant temperature between 50° and 60°F (10° and 16°C). Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building. In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water.
Geothermal Energy: The Earth's heat-called geothermal energy-escapes as steam at a hot springs in Nevada.
The Earth's heat-called geothermal energy-escapes as steam at a hot springs in Nevada. Credit: Sierra Pacific
In the United States, most geothermal reservoirs of hot water are located in the western states, Alaska, and Hawaii. Wells can be drilled into underground reservoirs for the generation of electricity. Some geothermal power plants use the steam from a reservoir to power a turbine/generator, while others use the hot water to boil a working fluid that vaporizes and then turns a turbine. Hot water near the surface of Earth can be used directly for heat. Direct-use applications include heating buildings, growing plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as pasteurizing milk.
Hot dry rock resources occur at depths of 3 to 5 miles everywhere beneath the Earth's surface and at lesser depths in certain areas. Access to these resources involves injecting cold water down one well, circulating it through hot fractured rock, and drawing off the heated water from another well. Currently, there are no commercial applications of this technology. Existing technology also does not yet allow recovery of heat directly from magma, the very deep and most powerful resource of geothermal energy.
Diffraction refers to various phenomena which occur when a wave encounters an obstacle. It is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings. Similar effects are observed when light waves travel through a medium with a varying refractive index or a sound wave through one with varying acoustic impedance. Diffraction occurs with all waves, including sound waves, water waves, and electromagnetic waves such as visible light, x-rays and radio waves. As physical objects have wave-like properties (at the atomic level), diffraction also occurs with matter and can be studied according to the principles of quantum mechanics.
ReplyDeleteWhile diffraction occurs whenever propagating waves encounter such changes, its effects are generally most pronounced for waves where the wavelength is on the order of the size of the diffracting objects. If the obstructing object provides multiple, closely-spaced openings, a complex pattern of varying intensity can result. This is due to the superposition, or interference, of different parts of a wave that traveled to the observer by different paths (see diffraction grating).
The formalism of diffraction can also describe the way in which waves of finite extent propagate in free space. For example, the expanding profile of a laser beam, the beam shape of a radar antenna and the field of view of an ultrasonic transducer are all explained by diffraction theory.
Diffusion is a time-dependent process, constituted by random motion of given entities and causing the statistical distribution of these entities to spread in space. The concept of diffusion is tied to notion of mass transfer, driven by a concentration gradient.
ReplyDeleteThe concept of diffusion emerged in the physical sciences. The paradigmatic examples were heat diffusion, molecular diffusion and Brownian motion. Their mathematical description was elaborated by Joseph Fourier in 1822, Adolf Fick in 1855 and by Albert Einstein in 1905.
Applications outside physics were pioneered by Louis Bachelier who in 1900 used a random walk model to describe price fluctuations on financial markets. In a less quantitative way, the concept of diffusion is invoked in the social sciences to describe the spread of ideas (Diffusion of innovations, Lexical
diffusion, Trans-cultural diffusion).
Other types of diffusion
* Atomic diffusion, in solids.
* Eddy diffusion, incoarse-grained description of turbulent flow
* Effusion of a gas through small holes.
* Electronic diffusion, resulting in an electric current called the diffusion current.
* Facilitated diffusion, present in some organisms.
* Gaseous diffusion, used for isotope separation
* Heat equation, diffusion of thermal energy
* Itō diffusion, mathematisation of Brownian motion, continuous stochastic process.
* Knudsen diffusion of gas in long pores with frequent wall collisions
* Momentum diffusion, ex. the diffusion of the hydrodynamic velocity field
* Osmosis is the diffusion of water through a cell membrane.
* Photon diffusion
* Reverse diffusion, against the concentration gradient, in phase separation
* Rotational diffusion, random reorientions of molecules
* Surface diffusion, diffusion of adparticles on a surface
mark jayson r bercilla.
ReplyDeletebouyancy
bouyancy means tendency of an object immersed in a fluid to float. boats float in water in balloons float in air due to bouyancy everything pretty much nash bouyant forces the battle ship arizona on the bottom of pearl harbor wont float but bouyant force make it lighter.you weigt less because of the bouyant force on air.
acceleration is the change in velocity over time.[1] Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, i.e. a line, acceleration is the rate at which something speeds up or slows down. However, as a vector quantity, acceleration is also the rate at which direction changes.[2][3] Acceleration has the dimensions L T−2. In SI units, acceleration is measured in metres per second squared (m/s2).
ReplyDeleteIn common speech, the term acceleration commonly is used for an increase in speed (the magnitude of velocity); a decrease in speed is called deceleration. In physics, a change in the direction of velocity also is an acceleration: for rotary motion, the change in direction of velocity results in centripetal (toward the center) acceleration; where as the rate of change of speed is a tangential acceleration.
In classical mechanics, for a body with constant mass, the acceleration of the body is proportional to the resultant (total) force acting on it (Newton's second law):
\mathbf{F} = m\mathbf{a} \quad \to \quad \mathbf{a} = \mathbf{F}/m
A quark is one of the fundamental particles in physics. They join together to form hadrons, such as protons and neutrons. The study of quarks and the interactions between them is called quantum chromodynamics.
ReplyDeleteThe anti-particle of a quark is the antiquark. Quarks and antiquarks are the only two fundamental particles that interact through all four fundamental forces of physics.
A quark exhibits confinement, which means that the quarks are not observed independently but always in combination with other quarks. This makes determining the properties (mass, spin, and parity) impossible to measure directly; these traits must be inferred from the particles composed of them.
These measurements indicate a non-integer spin (either +1/2 or -1/2), so quarks are fermions and follow the Pauli Exclusion Principle. There are 6 flavours of quarks: up, down, strange, charm, bottom, and top.
The flavour of the quark determines its properties. Quarks with a charge of +(2/3)e are called up-type quarks and those with a charge of -(1/3)e are called down-type. There are three generations of quarks, based on pairs of weak positive/negative weak isospin. The first generation are up & down quarks, the second generation are strange & charm quarks, the third generation are top & bottom quarks.
All quarks have a baryon number (B = 1/3) and a lepton number (L = 0). The flavour determines certain other unique properties, described in individual descriptions. (See links to the right.)
*Transistor*
ReplyDeleteA transistor is a semiconductor device used to amplify or switch electronic signals. It is made of a solid piece of semiconductor material, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing through another pair of terminals. Because the controlled (output) power can be much more than the controlling (input) power, the transistor provides amplification of a signal. Some transistors are packaged individually but many more are found embedded in integrated circuits.
Transistor as an amplifier
Amplifier circuit, standard common-emitter configuration.
The common-emitter amplifier is designed so that a small change in voltage in (Vin) changes the small current through the base of the transistor and the transistor's current amplification combined with the properties of the circuit mean that small swings in Vin produce large changes in Vout.
It is important that the operating values of the transistor are chosen and the circuit designed such that as far as possible the transistor operates within a linear portion of the graph, such as that shown between A and B, otherwise the output signal will suffer distortion.
Various configurations of single transistor amplifier are possible, with some providing current gain, some voltage gain, and some both.
From mobile phones to televisions, vast numbers of products include amplifiers for sound reproduction, radio transmission, and signal processing. The first discrete transistor audio amplifiers barely supplied a few hundred milliwatts, but power and audio fidelity gradually increased as better transistors became available and amplifier architecture evolved.
Modern transistor audio amplifiers of up to a few hundred watts are common and relatively inexpensive.
Some musical instrument amplifier manufacturers mix transistors and vacuum tubes in the same circuit, as some believe tubes have a distinctive sound.
TOPIC:Phosphorus
ReplyDeletePhosphorus (pronounced /ˈfɒsfərəs/, FOS-fər-əs) is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks. Elemental phosphorus exists in two major forms - white phosphorus and red phosphorus. Although the term "phosphorescence", meaning glow after illumination, derives from phosphorus, glow of phosphorus originates from oxidation of the white (but not red) phosphorus and should be called chemiluminescence.
Due to its high reactivity, phosphorus is never found as a free element in nature on Earth. The first form of phosphorus to be discovered (white phosphorus, in 1669) emits a faint glow upon exposure to oxygen — hence its name given from Greek mythology, Φωσφόρος meaning "light-bearer" (Latin Lucifer), referring to the "Morning Star", the planet Venus.
Phosphorus is a component of DNA, RNA, ATP, and also the phospholipids which form all cell membranes. It is thus an essential element for all living cells. The most important commercial use of phosphorus-based chemicals is the production of fertilizers.
Phosphorus compounds are also widely used in explosives, nerve agents, friction matches, fireworks, pesticides, toothpaste and detergents.
Projectile motion refers to the motion of an object projected into the air at an angle. A few
ReplyDeleteexamples of this include a soccer ball begin kicked, a baseball begin thrown, or an athlete
long jumping. Even fireworks and water fountains are examples of projectile motion. In this
lesson you will learn the fundamentals of projectile motion. You will be given examples and
interesting facts. Finally, you will get to test your knowledge with a game called Water Balloons!.
A diaphragm is a thin rubber dome with a springy and flexible rim. It is inserted into the vagina, fits over the cervix and is held in place by vaginal muscles. A diaphragm holds spermicide in place over the cervix (opening to the uterus). Spermicide kills sperm, preventing fertilization. After intercourse, it should be left in place for 6-8 hours. Diaphragms are 86-94% effective as birth control.
ReplyDeleteDiaphragms may offer some limited protection against reproductive tract infections and HIV/AIDS. See Cervical Barriers Advancement Society for the latest information.
Use
Getting a diaphragm requires a fitting in a clinic. During the fitting, a fitting ring is inserted into the vagina. The largest ring that fits comfortably is usually the one chosen. Different types of diaphragms are available. You and your medical provider can decide between coil, flat, or arcing spring diaphragms.
Diaphragms can be inserted up to 2 hours before sex because spermicide is only effective for 2 hours. If you insert your diaphragm more than 2 hours before intercourse, you will have to insert more spermicide into your vagina. To do this, leave your diaphragm in and use an applicator to add more spermicide directly into the vagina. Every time a woman has intercourse, she will need to add more spermicide to her vagina with an applicator.
THE MANHATTAN PROJECT
ReplyDeleteLeslie Groves and J. Robert OppenheimerIn a national survey at the turn of the millennium, both journalists and the public ranked the dropping of the atomic bomb and the end of the Second World War as the top news stories of the twentieth-century. The advent of nuclear weapons, made possible by the Manhattan Project, not only helped bring an end to the Second World War -- it ushered in the atomic age and determined how the next war, the Cold War, would be fought.
The United States Department of Energy Office of History and Heritage Resources, with the assistance of a graduate fellow, has been developing an interactive web site on the Manhattan Project. When completed, The Manhattan Project: An Interactive History will total some 120,000 words and over 200 pages and 500 images, including photographs, maps, and drawings. The site is being implemented incrementally, with the "Events of the Manhattan Project" and "Resources Relating to the Manhattan Project" sections the first part to go online. Click on the Events or Resources buttons to the left for a listing of currently available pages.
The remaining sections are scheduled to go online in the near future. Click on the buttons to the left for listings of the projected web pages under each heading.
Lovely Guilleno
ReplyDeleteGamma decay
There are three types of radiation
the alpha decay, beta decay, and gamma decay
I was focused in the gamma decay type of radiation.
A gamma decay is a radioactive process in which an atomic nucleus loses energy by emitting a gamma ray without a change in its atomic or mass numbers.
And it is a decay of an unstable elementary particle by photon emission.
and also it is a stream of high-energy photons. When an element undergoes gamma decay its atomic number and mass number do not change.
Displacement is the shifting of actions from a desired target to a substitute target when there is some reason why the first target is not permitted or not available.
ReplyDeleteDisplacement may involve retaining the action and simply shifting the target of that action. Where this is not feasible, the action itself may also change. Where possible the second target will resemble the original target in some way.
Phobias may also use displacement as a mechanism for releasing energy that is caused in other ways.
Example
The boss gets angry and shouts at me. I go home and shout at my wife. She then shouts at our son. With nobody left to displace anger onto, he goes and kicks the dog.
A man wins the lottery. He turns to the person next to him and gives the person a big kiss.
A boy is afraid of horses. It turns out to be a displaced fear of his father.
I want to speak at a meeting but cannot get a word in edgeways. Instead, I start scribbling furiously.
A religious person who is sexually frustrated focuses their attention on food, becoming a gourmet.
A woman, rejected by her boyfriend, goes out with another man 'on the rebound'.
Discussion
Displacement occurs when the Id wants to do something of which the Super ego does not permit. The Ego thus finds some other way of releasing the psychic energy of the Id. Thus there is a transfer of energy from a repressed object-cathexis to a more acceptable object.
Displaced actions tend to be to into related areas or subjects. If I want to shout at a person but feel that I cannot, then shouting at somebody else is preferred to going to play the piano, although this may still be used if there is no other way I can release my anger.
Displacements are often quite satisfactory and workable mechanisms for releasing energy more safely.
The atom is a basic unit of matter consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons (except in the case of hydrogen-1, which is the only stable nuclide with no neutron). The electrons of an atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can remain bound to each other, forming a molecule. An atom containing an equal number of protons and electrons is electrically neutral, otherwise it has a positive or negative charge and is an ion. An atom is classified according to the number of protons and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determine the isotope of the element.[1]
ReplyDeleteThe name atom comes from the Greek ἄτομος/átomos, α-τεμνω, which means uncuttable, or indivisible, something that cannot be divided further. The concept of an atom as an indivisible component of matter was first proposed by early Indian and Greek philosophers. In the 17th and 18th centuries, chemists provided a physical basis for this idea by showing that certain substances could not be further broken down by chemical methods. During the late 19th and early 20th centuries, physicists discovered subatomic components and structure inside the atom, thereby demonstrating that the 'atom' was divisible. The principles of quantum mechanics were used to successfully model the atom.[2][3]
Relative to everyday experience, atoms are minuscule objects with proportionately tiny masses. Atoms can only be observed individually using special instruments such as the scanning tunneling microscope. Over 99.9% of an atom's mass is concentrated in the nucleus,[note 1] with protons and neutrons having roughly equal mass. Each element has at least one isotope with unstable nuclei that can undergo radioactive decay. This can result in a transmutation that changes the number of protons or neutrons in a nucleus.[4] Electrons that are bound to atoms possess a set of stable energy levels, or orbitals, and can undergo transitions between them by absorbing or emitting photons that match the energy differences between the levels. The electrons determine the chemical properties of an element, and strongly influence an atom's magnetic properties
Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. In this case the energy extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head. To obtain very high head, water for a hydraulic turbine may be run through a large pipe called a penstock.[3]
ReplyDeletePumped storage hydroelectricity produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine. Pumped storage schemes currently provide the only commercially important means of large-scale grid energy storage and improve the daily capacity factor of the generation system. Hydroelectric plants with no reservoir capacity are called run-of-the-river plants, since it is not then possible to store water. A tidal power plant makes use of the daily rise and fall of water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot waterwheels.
junavil hangco
ReplyDeleteHYDROELECTRICPOWER
Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. In this case the energy extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head. To obtain very high head, water for a hydraulic turbine may be run through a large pipe called a penstock.[3]
Pumped storage hydroelectricity produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine. Pumped storage schemes currently provide the only commercially important means of large-scale grid energy storage and improve the daily capacity factor of the generation system. Hydroelectric plants with no reservoir capacity are called run-of-the-river plants, since it is not then possible to store water. A tidal power plant makes use of the daily rise and fall of water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot waterwheels.
Ivylen aparente
ReplyDeleteatmospheric pressure
Atmospheric pressure is defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Low pressure areas have less atmospheric mass above their location, whereas high pressure areas have more atmospheric mass above their location. Similarly, as elevation increases there is less overlying atmospheric mass, so that pressure decreases with increasing elevation. A column of air one square inch in cross-section, measured from sea level to the top of the atmosphere, would weigh approximately 14.7 lbf (65 N).
The standard atmosphere (symbol: atm) is a unit of pressure and is defined as being equal to 101,325 Pa or 101.325 kPa. [1][2] The following units are equivalent, but only to the number of decimal places displayed: 760 mmHg (torr), 29.92 inHg, 14.696 PSI, 1013.25 millibars. One standard atmosphere is standard pressure used for pneumatic fluid power (ISO R554), and in the aerospace (ISO 2533) and petroleum (ISO 5024) industries.
jennifer manlapas
ReplyDeleteMomentum
In classical mechanics, momentum (pl. momenta; SI unit kg·m/s, or, equivalently, N·s) is the product of the mass and velocity of an object (p = mv). For more accurate measures of momentum, see the section "modern definitions of momentum" on this page. It is sometimes referred to as linear momentum to distinguish it from the related subject of angular momentum. Linear momentum is a vector quantity, since it has a direction as well as a magnitude. Angular momentum is a pseudovector quantity because it gains an additional sign flip under an improper rotation. The total momentum of any group of objects remains the same unless outside forces act on the objects (law of conservation of momentum).
Momentum is a conserved quantity, meaning that the total momentum of any closed system (one not affected by external forces) cannot change. Although originally seen to be due to Newton's laws, this law is also true in special relativity, and with appropriate definitions a (generalized) momentum conservation law holds in electrodynamics, quantum mechanics, quantum field theory, and general relativity.
topic: refraction
ReplyDelete-it is the change in direction of a wave due to a change in its speed. This is most commonly observed when a wave passes from one medium to another at an angle. Refraction of light is the most commonly observed phenomenon, but any type of wave can refract when it interacts with a medium, for example when sound waves pass from one medium into another or when water waves move into water of a different depth. Refraction is described by Snell's law, which states that the angle of incidence θ1 is related to the angle of refraction θ2 by
\frac{\sin\theta_1}{\sin\theta_2} = \frac{v_1}{v_2} = \frac{n_2}{n_1}
where v1 and v2 are the wave velocities in the respective media, and n1 and n2 the refractive indices. In general, the incident wave is partially refracted and partially reflected; the details of this behavior are described by the Fresnel equations.
This comment has been removed by the author.
ReplyDeletemagnet
ReplyDeleteMagnets and their associated magnetic field lines. A permanent magnet (such as a bar or disk …
Magnets and their associated magnetic field lines. A permanent magnet (such as a bar or disk … (credit: © Merriam-Webster Inc.)
Any material capable of attracting iron and producing a magnetic field outside itself. By the end of the 19th century, all known elements and many compounds had been tested for magnetism, and all were found to have some magnetic property. However, only three elements — iron, nickel, and cobalt — exhibit ferromagnetism. See also compass, electromagnet.
topic: reflection
ReplyDeleteReflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The law of reflection says that for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected. Mirrors exhibit specular reflection.
Laws of regular reflection
If the reflecting surface is very smooth, the reflection of light that occurs is called specular or regular reflection. The laws of reflection are as follows:
1. The incident ray, the reflected ray and the normal to the reflection surface at the point of the incidence lie in the same plane.
2. The angle which the incident ray makes with the normal is equal to the angle which the reflected ray makes to the same normal.
3. Light paths are reversible.
Other types of reflection
*Diffuse reflection
*Retroreflection
*Complex conjugate reflection
*Neutron reflection
*Sound reflection
*Seismic reflection
topic: plant
ReplyDeleteplant
Any organism in the kingdom Plantae, consisting of multicellular, eukaryotic life forms (see eukaryote) with six fundamental characteristics: photosynthesis as the almost exclusive mode of nutrition, essentially unlimited growth at meristems, cells that contain cellulose in their walls and are therefore somewhat rigid, the absence of organs of movement, the absence of sensory and nervous systems, and life histories that show alternation of generations. No definition of the kingdom completely excludes all nonplant organisms or even includes all plants. Many plants, for example, are not green and thus do not produce their own food by photosynthesis, being instead parasitic on other living plants (see parasitism). Others obtain their food from dead organic matter. Many animals possess plantlike characteristics, such as a lack of mobility (e.g., sponges) or the presence of a plantlike growth form (e.g., some corals and bryozoans), but in general such animals lack other plant characteristics. Some past classification systems (see taxonomy) placed difficult groups such as protozoans, bacteria, algae, slime molds, and fungi (see fungus) in the plant kingdom, but structural and functional differences between these organisms and plants have convinced most scientists to classify them elsewhere.
grace ilocto
ReplyDeleteinertia
Inertia is the name for the tendency of an object in motion to remain in motion, or an object at rest to remain at rest, unless acted upon by a force. This concept was quantified in Newton's First Law of Motion.
Inherent property of a body that makes it oppose any force that would cause a change in its motion. A body at rest and a body in motion both oppose forces that might cause acceleration. The inertia of a body can be measured by its mass, which governs its resistance to the action of a force, or by its moment of inertia about a specified axis, which measures its resistance to the action of a torque about the same axis.
According to Newton’s law of inertia, the tendency of a body that is at rest to remain at rest and a body that is in motion to continue in motion with constant speed in the same straight line unless acted on by an outside force.
Coulomb's law is a law of physics describing the electrostatic interaction between electrically charged particles. It was studied and first published in 1783 by French physicist Charles Augustin de Coulomb and was essential to the development of the theory of electromagnetism. Nevertheless, the dependence of the electric force with distance (inverse square law) had been proposed previously by Joseph Priestley[1] and the dependence with both distance and charge had been discovered, but not published, by Henry Cavendish, prior to Coulomb's works.
ReplyDeleteCoulomb's law may be stated in scalar form as follows:
The magnitude of the electrostatic force between two point electric charges is directly proportional to the product of the magnitudes of each of the charges and inversely proportional to the square of the distance between the two charges.
RHINA SURIO.
ReplyDeleteSOUND
Sound is a travelling wave which is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.[1]
The mechanical vibrations that can be interpreted as sound are able to travel through all forms of matter: gases, liquids, solids, and plasmas. The matter that supports the sound is called the medium. Sound cannot travel through vacuum.
Speed of light
ReplyDeleteI will share to you about the speed of light
The speed of light is a physical constant. Its value is exactly 299,792,458 metres per second,[1][2] often approximated as 300,000 kilometres per second or 186,000 miles per second (see the table on the right for values in other units). It is the speed of electromagnetic radiation (such as radio waves, visible light, or gamma rays) in vacuum, where there are no atoms, molecules or other types of matter that can slow it down.
For much of human history, it was not known whether light was transmitted instantaneously or simply very quickly. In the 17th century, Ole Rømer first demonstrated that it travelled at a finite speed by studying the apparent motion of Jupiter's moon Io. After centuries of increasingly precise measurements, in 1975 the speed of light was known to be 299,792,458 m/s with a relative measurement uncertainty of 4 parts per billion. In 1983, the metre was redefined in the International System of Units (SI) as the distance travelled by light in vacuum in 1⁄299,792,458 of a second. As a result, the numerical value of c in metres per second is now fixed exactly by the definition of the metre.
According to the theory of special relativity, c connects space and time in the unified structure of spacetime, and its square is the constant of proportionality between mass and energy (E = mc2) In any inertial frame of reference, independently of the relative velocity of the emitter and the observer, c is the speed of all massless particles and associated fields, including all electromagnetic radiation in free space,and it is believed to be the speed of gravity and of gravitational waves. It is an upper bound on the speed at which energy, matter, and information can travel, as surpassing it "would lead to the destruction of the essential relation between cause and effect.".Its finite value is a limiting factor in the speed of operation of electronic devices.
The actual speed at which light propagates through transparent materials, such as glass or air, is less than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c / v). For example, for visible light the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200,000 km/s; the refractive index of air for visible light is about 1.0003, so the speed of light in air is very close to c.
The speed of light (usually denoted c) is a physical constant. Its value is exactly 299,792,458 metres per second, often approximated as 300,000 kilometres per second or 186,000 miles per second (see the table on the right for values in other units). It is the speed of electromagnetic radiation (such as radio waves, visible light, or gamma rays) in vacuum, where there are no atoms, molecules or other types of matter that can slow it down.
ReplyDeleteFor much of human history, it was not known whether light was transmitted instantaneously or simply very quickly. In the 17th century, Ole Rømer first demonstrated that it travelled at a finite speed by studying the apparent motion of Jupiter's moon Io. After centuries of increasingly precise measurements, in 1975 the speed of light was known to be 299,792,458 m/s with a relative measurement uncertainty of 4 parts per billion. In 1983, the metre was redefined in the International System of Units (SI) as the distance travelled by light in vacuum in 1⁄299,792,458 of a second. As a result, the numerical value of c in metres per second is now fixed exactly by the definition of the metre.
According to the theory of special relativity, c connects space and time in the unified structure of spacetime, and its square is the constant of proportionality between mass and energy (E = mc2). In any inertial frame of reference, independently of the relative velocity of the emitter and the observer, c is the speed of all massless particles and associated fields, including all electromagnetic radiation in free space, and it is believed to be the speed of gravity and of gravitational waves. It is an upper bound on the speed at which energy, matter, and information can travel, as surpassing it "would lead to the destruction of the essential relation between cause and effect." Its finite value is a limiting factor in the speed of operation of electronic devices.
The actual speed at which light propagates through transparent materials, such as glass or air, is less than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c / v). For example, for visible light the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200,000 km/s; the refractive index of air for visible light is about 1.0003, so the speed of light in air is very close to c.
hello sir????
ReplyDeletehello sir?
ReplyDelete"NEWTON'S THREE LAW OF MOTION"
ReplyDeleteLet us begin our explanation of how Newton changed our undestanding of the Universe by enumerating his Three Laws of Motion.
NEWTON'S FIRST LAW OF MOTION:
I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
=This we recognize as essentially Galileo's concept of inertia,and this is often termed simply the "LAW OF INERTIA".
NEWTON'S SECOND LAW OF MOTION:
II. The relations between an object's mass M,its acceleration A,and the appleied force F is F=ma. Acceleration and force are vectors (as indicated by their symblos being displayedin slant bold font);in this law the direction of the force vector is the same as the direction of the acceleration vector.
=This is the most powerful of Newtons three Laws,because it allows quantitative calculations o dynamics: how do velocities change when forces are applied. Notice the fundemental difference between Newton's Law and the dynamics of Aristotle: according to Newton,a force causes only a change in velocity (an acceleration); it does not maintain the velocity as Aristotle held.
This is sometimes summarized by saying that under Newton,F=ma,but under Aristotle F=mv,where v is the velocity. Thus,according to Aristotle there is only a velocity if there is force,but according to Newton an object with a certain velocity maintains that velocity unless a force acts on it to cause an acceleartion (that is,that is,a change in the velocity). As we have noted earlier in conjuction with discussion of Galelio,Aristotle's view seems to be more in accord with common sense,but that is because of a failure to appreciate the role played by frictional forces. Once account taken of all forces acting in a given situation it is the dynamics of Galelio and Newton,not of Aristotle,that are found to be in accord the observations.
NEWTON'S THIRD LAW OF MOTION:
III. For every action there is an equal and opposite reaction.
=This law is exemplified by what happens if we step off a boat onto the bank of a lake: as we move in the direction of the shore,the boat tends to move in the opposite direction (leaving us facedown in the water,if we aren't careful!).
topic:accelaration
ReplyDeleteWhen you talk about weight and forces you have to conclude that you are dealing with a falling body, and that other forces such as air resistance etc are ignored: Now your question:
If a body is falling towards the earth it experiences a downward force equivalent to its weight: that is mass of the body multiplied by the acceleration due to gravity.
Unbalanced or Resultant force on body = mass * acceleration. This is measured in N
As an example, a 100kg man will have a downward force acting on him of 981N
This force is in actual fact an unbalanced force acting downwards, and the acceleration will be 9.81m/s³
As far as I can determine, the only possible way that an unbalanced force equal to the weight of the man can affect the acceleration is if a further 981N force is applied downwards on the man. The total force acting downwards on the man will then be 1,962N, and his acceleration downwards will be 19.62m/s².
If a 981N force is applied upward on the man, he will stop falling, his velocity will be zero. But this is not an unbalanced force: It is a force exactly in equilibrium with the downward force on the man.
I have tried to answer this as best I can. Maybe I am missing some fundamental point. But I must admit that I do not really understand the wording of the question.
topic:beta particles
ReplyDeleteBeta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles emitted are a form of ionizing radiation also known as beta rays. The production of beta particles is termed beta decay. They are designated by the Greek letter beta (β). There are two forms of beta decay, β− and β+, which respectively give rise to the electron and the positron.
USES:
Beta particles can be used to treat health conditions such as eye and bone cancer, and are also used as tracers. Strontium-90 is the material most commonly used to produce beta particles. Beta particles are also used in quality control to test the thickness of an item, such as paper, coming through a system of rollers. Some of the beta radiation is absorbed while passing through the product. If the product is made too thick or thin, a correspondingly different amount of radiation will be absorbed. A computer program monitoring the quality of the manufactured paper will then move the rollers to change the thickness of the final product.
Inverse beta decay of a radioactive tracer isotope is the source of the positrons used in positron emission tomography (PET scan).
topic:diodes
ReplyDeleteIn electronics, a diode is a two-terminal electronic component that conducts electric current in only one direction. The term usually refers to a semiconductor diode, the most common type today, which is a crystal of semiconductor connected to two electrical terminals, a P-N junction. A vacuum tube diode, now little used, is a vacuum tube with two electrodes; a plate and a cathode.
The most common function of a diode is to allow an electric current in one direction (called the diode's forward direction) while blocking current in the opposite direction (the reverse direction). Thus, the diode can be thought of as an electronic version of a check valve. This unidirectional behavior is called rectification, and is used to convert alternating current to direct current, and remove modulation from radio signals in radio receivers.
However, diodes can have more complicated behavior than this simple on-off action, due to their complex non-linear electrical characteristics, which can be tailored by varying the construction of their P-N junction. These are exploited in special purpose diodes that perform many different functions. Diodes are used to regulate voltage (Zener diodes), electronically tune radio and TV receivers (varactor diodes), generate radio frequency oscillations (tunnel diodes), and produce light (light emitting diodes).
Diodes were the first semiconductor electronic devices. The discovery of crystals' rectifying abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's whisker diodes were made of crystals of minerals such as galena. Today most diodes are made of silicon, but other semiconductors such as germanium are sometimes used.
angeline armada
ReplyDeletetopic:acceleration
When you talk about weight and forces you have to conclude that you are dealing with a falling body, and that other forces such as air resistance etc are ignored: Now your question:
If a body is falling towards the earth it experiences a downward force equivalent to its weight: that is mass of the body multiplied by the acceleration due to gravity.
Unbalanced or Resultant force on body = mass * acceleration. This is measured in N
As an example, a 100kg man will have a downward force acting on him of 981N
This force is in actual fact an unbalanced force acting downwards, and the acceleration will be 9.81m/s³
As far as I can determine, the only possible way that an unbalanced force equal to the weight of the man can affect the acceleration is if a further 981N force is applied downwards on the man. The total force acting downwards on the man will then be 1,962N, and his acceleration downwards will be 19.62m/s².
If a 981N force is applied upward on the man, he will stop falling, his velocity will be zero. But this is not an unbalanced force: It is a force exactly in equilibrium with the downward force on the man.
I have tried to answer this as best I can. Maybe I am missing some fundamental point. But I must admit that I do not really understand the wording of the question.
topic:speed
ReplyDeleteIn kinematics, the instantaneous speed of an object (denoted v) is the magnitude of its instantaneous velocity (the rate of change of its position); it is thus the scalar equivalent of velocity. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero.
Like velocity, speed has the dimensions of a length divided by a time; the SI unit of speed is the meter per second, but the most usual unit of speed in everyday usage is the kilometer per hour or, in certain countries, the mile per hour.
The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in vacuum c = 299,792,458 meters per second, approximately 1079 million kilometers (671 million miles) per hour. Matter cannot quite reach the speed of light, as this would require an infinite amount of energy.
TOPIC:LAWS OF REFLECTION
ReplyDeleteA light ray is a stream of light with the smallest possible cross-sectional area. (Rays are theoretical constructs.) The incident ray is defined as a ray approaching a surface. The point of incidence is where the incident ray strikes a surface. The normal is a construction line drawn perpendicular to the surface at the point of incidence. The reflected ray is the portion of the incident ray that leaves the surface at the point of incidence. The angle of incidence is the angle between the incident ray and the normal. The angle of reflection is the angle between the normal and the reflected ray.
SIR....CHURIE LATE KAMI HEHEHHE(^^)