1. 7.2 Conservation of Energy

2. Kinetic energy can be converted into potential energy and vice versa.
Energy Flow
Kinetic energy can be converted into potential energy and vice versa.

3. Conservation of Energy
The idea that energy transforms from one form into another without a change in the total amount is called the law of conservation of energy.
Total energy before = total energy after
People concerned about “running out” of energy really mean “running out of certain types of energy” that are easy to transform.

4. Conservation of Energy Example
When you throw a ball in the air, the energy transforms from kinetic to potential and then back to kinetic.

5. Conservation of Energy Example
A 0.5 kg ball moving at a speed of 3 m/s rolls up a hill. How high does the ball roll before it stops?

6. Potential & Kinetic Energy Example
A 2.0 kg rock is at the edge of a cliff 20. meters above a lake. The rock becomes loose and falls toward the water below. What is the potential energy and the kinetic energy of the rock at the top of the hill and when it is halfway down? Its speed is 14. m/s at the halfway point.
Potential (top) =
Potential (halfway) =
Kinetic (top) =
Kinetic (halfway) =