C
Calorie
The amount of heat needed to raise the temperature of one gram of water by one degree Celsius. 1 cal = 4.19 J.
Celsius
A scale for measuring temperature, defined such that water freezes at 0ºC and boils at 100ºC. 0ºC = 273 K.
Center of curvature
With spherical mirrors, the center of the sphere of which the mirror is a part. All of the normals pass through it.
Center of mass
Given the trajectory of an object or system, the center of mass is the point that has the same acceleration as the object or system as a whole would have if its mass were concentrated at that point. In terms of force, the center of mass is the point at which a given net force acting on a system will produce the same acceleration as if the system’s mass were concentrated at that point.
Centripetal acceleration
The acceleration of a body experiencing uniform circular motion. This acceleration is always directed toward the center of the circle.
Centripetal force
The force necessary to maintain a body in uniform circular motion. This force is always directed radially toward the center of the circle.
Chain reaction
The particles and energy released by the fission or fusion of one atom may trigger the fission or fusion of further atoms. In a chain reaction, fission or fusion is rapidly transferred to a large number of atoms, releasing tremendous amounts of energy.
Charles’s Law
For a gas held at constant pressure, temperature and volume are directly proportional.
Coefficient of kinetic friction
The coefficient of kinetic friction, , for two materials is the constant of proportionality between the normal force and the force of kinetic friction. It is always a number between zero and one.
Coefficient of linear expansion
A coefficient that tells how much a material will expand or contract lengthwise when it is heated or cooled.
Coefficient of static friction
The coefficient of static friction, for two materials is the constant of proportionality between the normal force and the maximum force of static friction. It is always a number between zero and one.
Coefficient of volume expansion
A coefficient that tells how much the volume of a solid will change when it is heated or cooled.
Coherent light
Light such that all of the associated waves have the same wavelength and are in phase.
Collision
When objects collide, each object feels a force for a short amount of time. This force imparts an impulse, or changes the momentum of each of the colliding objects. The momentum of a system is conserved in all kinds of collisions. Kinetic energy is conserved in elastic collisions, but not in inelastic collisions. In a perfectly inelastic collision, the colliding objects stick together after they collide.
Completely inelastic collision
A collision in which the colliding particles stick together.
Component
Any vector can be expressed as the sum of two mutually perpendicular component vectors. Usually, but not always, these components are multiples of the basis vectors, and ; that is, vectors along the x-axis and y-axis. We define these two vectors as the x- and y-components of the vector.
Compression
An area of high air pressure that acts as the wave crest for sound waves. The spacing between successive compressions is the wavelength of sound, and the number of successive areas of compression that arrive at the ear per second is the frequency, or pitch, of the sound.
Concave lens
Also called a diverging lens, a lens that is thinner in the middle than at the edges. Concave lenses refract light away from a focal point.
Concave mirror
A mirror that is curved such that its center is farther from the viewer than the edges, such as the front of a spoon. Concave mirrors reflect light through a focal point.
Conduction
Heat transfer by molecular collisions.
Conservation of Angular Momentum
If the net torque acting on a rigid body is zero, then the angular momentum of the body is constant or conserved.
Conservation of momentum
The principle stating that for any isolated system, linear momentum is constant with time.
Constant of proportionality
A constant in the numerator of a formula.
Constructive interference
The amplification of one wave by another, identical wave of the same sign. Two constructively interfering waves are said to be “in phase.”
Convection
Heat transfer via the mass movement of molecules.
Convex lens
Also called a converging lens, a lens that is thicker in the middle than at the edges. Convex lenses refract light through a focal point.
Convex mirror
A mirror that is curved such that its center is closer to the viewer than the edges, such as a doorknob. Convex mirrors reflect light away from a focal point.
Cosine
The cosine of an angle in a right triangle is equal to the length of the side adjacent to the angle divided by the length of the hypotenuse.
Crest
The points of maximum displacement along a wave. In traveling waves, the crests move in the direction of propagation of the wave. The crests of standing waves, also called anti-nodes, remain in one place.
Critical angle
For two given media, the smallest angle of incidence at which total internal reflection occurs.
Cross product
A form of vector multiplication, where two vectors are multiplied to produce a third vector. The cross product of two vectors, A and B, separated by an angle, , is , where is a unit vector perpendicular to both A and B. To deine which direction points, you must use the right-hand rule.
Cycle
In oscillation, a cycle occurs when an object undergoing oscillatory motion completes a “round-trip.” For instance, a pendulum bob released at angle has completed one cycle when it swings to and then back to again. In period motion, a cycle is the sequence through which a system once during each oscil-lation. A cycle can consist of one trip up and down for a piece of stretched string, or of a compression followed by a rarefaction of air pressure for sound waves.