1. ATB - Work Review
How much Work is done in lifting a 5 N book 3 meters?
How much Work is done in carrying that same book up a flight of stairs that are 2 meters long and 3 meters high?

2. Physics Chapter 7
ENERGY

3. Mechanical Energy Potential Kinetic
Energy that is stored because of its position relative to something else.
Kinetic
Energy of motion

4. Potential Energy Energy that is stored because of its position relative to something else.
Examples 
A drawn bow
A stretched or compressed spring
Slingshot
Chemical energy
Water in an elevated reservoir
Ram of a pile driver
Gravitational Potential Energy

5. Potential Energy Gravitational Potential Energy PE = mgh
PE due to an elevated position
Amount of PE is equal to the Work done in lifting it
W = Fd
The force (F) needed to lift it is the force equal and opposite to the objects weight  Fw = mg
The distance (d) is the height, h above the Earth
PE = mgh
Only changes in PE are meaningful. That is, how much PE is converted into some other form.

6. Potential Energy
It does not matter how the object gets to the height, h. The PE of the ball depends only on the height, not the path taken there. Whether it is lifted, pushed up a ramp, or carried up stairs, the PE is equal.

7. Example #1 A 2000 kg car is picked up by a crane to a height of 10 m.
A) What is the PE of the car?
B) How much work was done by the crane? 17

8. Kinetic Energy Energy of Motion
Examples 
Pendulum
Roller Coaster Car
Any object that is in motion, i.e. has a velocity

9. Kinetic Energy Depends on… Velocity Mass
Kinetic Energy = ½ mass x velocity2
Variable: KE
Unit: Joule
Equation: KE = ½ mv2

10. Example #2
A 6.0kg cat runs after a mouse at 10.0m/s. What is the cat’s kinetic energy?