# Shared Flashcard Set

## Details

Section 8 Energy Vocabulary
Vocabulary Section 8 Energy
15
Physics
08/13/2011

Term
 efficiency
Definition
 In a machine, the ratio of useful energy output to total energy input, or the percentage of the work input that is converted to work output
Term
 fuel cell
Definition
 A devise in which hydrogen and oxygen are compressed at electrodes to produce water and electric current
Term
 fulcrum
Definition
 The pivot point of a lever
Term
 joule
Definition
 The SI unit of work and of all other forms of energy. One joule (symbol J) of work is done when a force of one Newton is exerted on an object move one meter in the direction of the force
Term
 kinetic energy
Definition
 Energy of motion, equal to half the mass multiplied by the speed squared
Term
 law of conservation of energy
Definition
 Energy cannot be created or destroyed. It may be transformed from one form into another, but the total amount of energy never changes
Term
 lever
Definition
 A simple machine, made of a bar that turns about a fixed point
Term
 machine
Definition
 A device for increasing (or decreasing) a force or simply changing the direction of a force
Term
Definition
 The ratio of output force to input force for a machine
Term
 mechanical energy
Definition
 The energy due to the position or the movement of something; potential or kinetic energy (or a combination of both)
Term
 potential energy
Definition
 Energy of position, usually related to the relative position of two things, such as a stone and Earth, or an electron and a nucleus
Term
 pulley
Definition
 A type of lever that is a wheel with a groove in its rim, which is used to change the direction of a force exerted by a rope or cable. A pulley or system of pulleys can also multiply forces
Term
 watt
Definition
 The SI unit of power. One watt is expended when one joule of work is done in one second
Term
 work
Definition
 The product of the force on an object and the distance through which the object is moved (when force is constant and motion is in a straight line in the direction of the force); measured in joules
Term
 work-energy theorem
Definition
 The theorem that states that whenever work is done, energy changes
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