1. Chapter 7
Potential Energy

2. Gravitational Potential Energy
The higher you are, the more energy you have.

3. Conservation of Energy

4. Conservation of Energy (no friction)

5. Conservation of Energy
What is the speed v of the ball at the bottom if the ball is released from rest? h

6. Example 2
If the ball is initially travelling at v0, what is the speed v of the ball when it is at h/3? h
h/3

7. Find the final speed

8. Roller Coaster
A roller coaster slides down a frictionless track at height h with initial speed v0. Find the speed at A.

9. Pendulum

10. Potential energy In a spring

11. How fast will it go?

12. Wf Work done by friction (Non-conservative force)

13. Two Potential Energy?
Later in Chapter 11, we will learn another equation for gravitational potential energy:
PEG=mgh is only true near the planet’s surface (where g is a constant). Far away the gravitational field gets weak (where g gets smaller) and PEG=mgh is no longer true.