1. 7.2 Energy

2. What is Energy?
Energy measures the ability for things to change themselves or to cause change in other things.
Examples:
changes in temperature, speed, position, pressure, or any other physical variable.

3. Some Forms of Energy

4. Units of Energy
Pushing a 1 kilogram object with a force of one newton for a distance of one meter uses one joule of energy.
1 J = 1 N•m

5. Potential Energy Potential energy: energy due to position.
- Systems or objects with potential energy are able to exert forces (exchange energy) as they change.

6. Potential Energy
EP = mgh
gravity (9.8 m/sec2)

7. Potential Energy Example
What is the potential energy of a 4 kg cat crouched in a tree 3 m off the ground?

8. Kinetic Energy Kinetic energy: energy due to motion
The amount of kinetic energy an object has equals the amount of work the object can do by exerting force as it stops.

9. Kinetic Energy Example
What is the kinetic energy of a 10 kg cat running at 5 m/s?