# Review of Work, Energy and Power

### Terms and Formulae

#### Terms

Conservative force  -  Any force which conserves mechanical energy, as opposed to a nonconservative force. See statement of conservation of mechanical energy.
Conservative System  -  A system in which energy is conserved.
Energy  -  The ability to do work.
Kinetic Energy  -  The energy of motion.
Nonconservative Force  -  Any force which does not conserve mechanical energy, as opposed to a conservative force.
Path independence  -  Property of conservative forces which states that the work done on any path between two given points is the same.
Potential energy  -  The energy of configuration of a conservative system. For formulae, see Definition of potential energy, gravitational potential energy, and Definition of potential energy given a position-dependent force.
Total mechanical energy  -  The sum of the kinetic and potential energy of a conservative system. See definition of total mechanical energy.
Work  -  A force applied over a distance. For formulas, see work done by a constant force parallel to displacement and work done by any constant force, and work done by a position-dependent force.
Joule  -  The units of work, equivalent to a Newton-meter. Also units of energy.
Power  -  Work done per unit time. For formulas, see Formula for average power, Definition of instantaneous power, and formula for instantaneous power.
Watt  -  Unit of power; equal to joule/second.

#### Formulas

 Work done by a constant force parallel to displacement W = Fx

 Work done by any constant force W = Fx cosθ

 Work-Energy Theorem W = ΔK

 Formula for average power =

 Definition of instantaneous power P =

 Formula for instantaneous power P = Fv cosθ

 Work done by a position-dependent force W = F(x)dx force.

 Definition of potential energy. ΔU = - W

 Gravitational potential energy. U G = mgh

 Statement of conservation of mechanical energy. Δ(U+K) = 0

 Definition of total mechanical energy. U + K = E

 Definition of potential energy given a position-dependent force. ΔU = - F(x)dx

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