Potential
and Kinetic
Energy
What is Energy???
The ability of an
object
To do work
Two Main Types of Energy
All Energy
Potential
Energy
Gravitation
Potential
Energy
Elastic
Potential
Energy
Kinetic
Energy
Chemical
Potential
Energy
What is Potential Energy?
o Energy that is stored
and waiting to be
used later
What is Gravitational Potential
Energy?
o Potential energy
due to an object’s
position
Don’t look down,
Rover!
Good boy!
o P.E. = mass x
height x gravity
ARRGGGG!! NO TRIANGLE
Gravity 
PE
Mass
Height
Find the Potential energy of a
20 kg bag of dog food
elevated 5 meters above the
ground on a shelf.
Mass = 20 kg
PE = mx g x h
Height = 5 m
PE = 20 kg x 9.8 m/s2 x 5 m
PE = 980 J
Find the potential energy of a
65 kg climber on top of Mt.
Everest ( 8800 m high).
Mass = 65 kg
PE = mx g x h
Height = 8800 m PE = 65 kg x 9.8 m/s2 x 8800 m
PE = 5 605 600 J
What is Elastic Potential Energy?
o Potential energy due compression or
expansion of an elastic object.
Notice the ball compressing
and expanding
What is Chemical Potential Energy?
o Potential energy
stored within the
chemical bonds of
an object
What is Kinetic Energy?
o Energy an object has due
to its motion
o K.E. = .5(mass x speed2)
Depends on …
Mass
and
Speed
KE = ½ mass x velocity2
KE = ½ M X V2
What is the kinetic energy of a 44kg
cheetah running at 31 m/s?
Mass = 44 kg
KE = ½ M x V2
Speed = 31 m/s
KE = .5 x 44 kg x (31 m/s)2
KE = 21 142 J
KE = ½ mass x velocity2
KE = ½ M X V2
What is the kinetic energy of a 400kg
elevator descending at a rate of 5 m/s?
Mass = 400 kg
KE = ½ M x V2
Speed = 5 m/s
KE = 400 kg x (5 m/s)2
KE = 5 000 J