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
|
