Work/Energy
Potential Energy
Definition of Potential Energy
Examples of Potential Energy
Types of Potential Energy
1
Work/Energy
Potential Energy
Definition of Potential Energy
Some types of conservative forces lend themselves to replacing
work by what we call potential energy.
Potential energy is so called because it measures the potential
of a particle to have kinetic energy.
Equations for various types of potential energy are always
given by the following equation
U of a an object for a particular force  Wdone by that force on an object
The unit of potential energy is the same as that for work.
2
Work/Energy
Potential Energy
Example with gravity (The system is gravity, the
block and the earth)
System
Δh
m
Work done by gravity (which is part of the system)
h
W    mgdy  mgh
0
3
Potential energy of
system
U g  mgh
Work/Energy
Potential Energy
Example with elastic force (The system is the
spring, the block and the thing that the thing to
which the other side of the spring attaches)
System
k
x
Felastic
Work done by gravity (which is part of the system)
1
2
W   kxdx   k x
0
2
Potential energy of
1
2
system
U sp  k x
2
x
4
Work/Energy
Potential Energy
Types of Potential Energy
Gravitational Potential Energy
U g mgh
m1m2
U g  G
r
Elastic Potential Energy
1
2
U sp  k x
2
5