1. Potential Energy Objectives P 205-212 Define potential energy
Calculate potential energy
Compare potential energy to kinetic energy

2. Potential Energy Measured in joules Stored energy
Elastic, chemical, nuclear and gravitational

3. Elastic Potential Energy

4. Chemical Potential Energy

5. Nuclear Potential Energy

6. Gravitational Potential Energy Energy due to an object’s position above the earth

7. Weight Related to Gravitational Potential Energy
Is not the same as mass
Formula: Fg=mg
Fg = weight in Newtons (n)
m= mass in kg
g= acceleration of gravity=9.81m/s2

8. Why are you weightless on the moon?

9. Gravitational Potential Energy
An object must have a height above ground to have Ep
The work required to move an object to a certain height is equal to its potential energy at that height.

10. Gravitational potential energy Formula
Ep = mgh
Ep= gravitational potential energy in joules (J)
m= mass in kg
g= gravity, 9.81m/s2
h=height in meters (m)

11. Ex) A shelf is 1. 8m above the floor. A book with a mass of 1
Ex) A shelf is 1.8m above the floor. A book with a mass of 1.2kg sits on the shelf. Calculate the gravitational potential energy.
Ep = mgh
=1.2kg x 9.81m/s2 x 1.8m
=21J

12. Energy Conversions
Energy is a conserved quantity: it can not be created or destroyed but it can be converted.
Ex) Gravitational energy will be converted to kinetic energy as an object returns to the ground

13. Ex) A 50. 0kg skier is at the top of a 100m hill
Ex) A 50.0kg skier is at the top of a 100m hill. What is his speed at the bottom of the hill?

14. Pendulum

15. Ex) If you did 565J of work on a 12kg box carrying it up a flight of stairs, how high are the stairs?
Ep = mgh