Terms You Should Know

acceleration: The rate of change of velocity with respect to time. It is calculated by subtracting the initial or starting velocity from the final velocity and dividing the difference by the time required to reach that velocity. It may be expressed by the formula a = v(f) - v(o)/t.
achromatic: An optical system that will transmit light without breaking it down into its component colors.
acoustics: The science of the production, transmission, and effect of sound waves.
adiabetic: Pertaining to any activity that is not accompanied by a gain or loss of heat.
anode: The positive terminal of an electrical current flow. In a vacuum tube, electrons flow from a cathode toward the anode.
Bohr theory: A commonly accepted concept of the atom introduced by Niels Bohr in 1913. It holds that each atom consists of a small, dense, positively charged nucleus surrounded by negatively charged electrons that move in fixed, defined orbits about the nucleus, the total number of electrons normally balancing the total positive charge of particles in the nucleus.
Boyle's law: The principle that the volume of a gas times its pressure is constant at a fixed temperature.
cathode: The negative terminal of an electric current system. In a vacuum tube, the filament serves as the cathode or source of electrons that are emitted.
centripetal force: The centrally-directed force exerted on a body moving in a curved direction. The root of this force is the body's impulse to travel in a straight line but that tendency being impeded by the force causing it to curve. e.g. a string exerts centripetal force on a spinning pail to keep it going in a complete circle
conduction: The transfer of heat by molecular motion from a source of high temperature to a region of lower temperature, tending toward a result of equalized temperatures.
convection: The mechanical transfer of heated molecules of a gas or liquid from a source to another area, as when a room is warmed by the movement of air molecules heated by a radiator.
Coulomb's law: The principle that an electrostatic force of attraction or repulsion between electrical charges is directly proportional to the product of the electrical charges and inversely proportional to the square of the distance between them.
Doppler Effect: the distortion of the reception of a point source due to either a moving source, moving receiver, or both.
density: a material's mass divided by its volume.
displacement: the staight-line distance from a moving object's original position to its final position.
dynamics: the branch of mechanics dealing with the motions of material bodies under the action of given forces
electromotive force: The force that causes the movement of electrons through an electrical circuit.
energy: The ability to perform work. Energy may be changed from one form to another, as from heat into light, but it normally cannot be created or destroyed.
fluid: that can flow; not solid; able to move and change shape without separating when under pressure
force: The influence on a body that causes it to accelerate, as expressed by the formula F = ma.
frequency: the number of oscillations or waves of an active repetitive motion in one second
friction: The force of resistance between two surfaces when the two surfaces are in contact with each other.
gravity: The force in the universe that attracts matter.
heat: A form of energy that results from the disordered motion of molecules. As the motion becomes more rapid and disordered, the amount of heat is increased.
Heisenberg's Uncertainty Principle: First stated by German physicist Werner Heisenberg, the idea that the exact position and momentum of a particle cannot be precisely detirmined at the same time. Only the probability of its location at a certain time can be predicted.
intensity: the property of a form of energy associated with its amplitude. With sound, intensity is usually referred to as loudness.
kinetic energy: Energy that is associated with the motion of an object as expressed by the formula KE - 1/2mv{2}.
mass: Simply, the amount of matter in an object. Mass has two primary manifestations: gravitationally and inertially
mechanics: A branch of physics that deals with the motion of objects.
momentum: The mathematical product of the mass of a moving object and its velocity, as expressed by the formula p = mv.
orbit: The path taken by a heavenly body during its periodic revolution around another body
phenomenon: pl. phenomena any fact, circumstance, or experience that is apparent to the senses and that can be scientifically appraised or defined
physics: The science dealing with the properties, changes, interactions, etc. of matter, and energy in which energy is considered to be continuous (classical) or discrete (quantum)
potential energy: Energy that is stored because of position or configuration, such as the gravitational energy of a weight that is positioned on the roof of a building.
power: The rate at which work is performed, as expressed by the formula P = W/t.
pressure: force exerted against an opposing body; thrust distributed over a surface; expressed in units of force per units of area
relativity: Einstein's observation that the pull of gravity and forces of acceleration cannot be distinguished from one another. One consequence is that the laws of physics must be studied in isolated frames of reference.
satellite: basically, a small object revolving around a much larger one. The moon is a satellite of the Earth, and the Earth is on eof the sun's satellites.
sound: longitudinal wave vibrations produced by variations in pressure carried by air or other media which can be perceived by the auditory senses as stimulation.
velocity: The speed with which an object travels over a specified distance during a measured amount of time. It may be expressed by the formula v = d/t.
Venturi Effect: The observable phenomenom of higher velocity fluids producing lower pressure than lower velocity fluids.
volume: The amount of space occupied in three dimensions, expressed in cubic units
wavelength: The distance between corresponding parts of a sinusoidal wave.
weight: The force on a body produced by the downward pull of gravity on it. It may be expressed by the formula W = mg, where m represents the mass of the object and g represents the acceleration of gravity. work The force applied to an object times the distance over which it is applied, as expressed by the formula W = Fd. Work may be independent of the energy expended.

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