1. Aim: How do we relate work and energy?
Do Now: Quiz
HW: Problem Set

2. Demos Pulling Christian around the room. Christian lifting up his desk
Christian holding his desk
Christians desk sitting there without Christian
Work done
No Work

3. Work Work: Energy transferred by a force. Energy: Ability to do work
Unit: Joule (J)
W = FIIdCosθ=ΔET
Nate pulls Christian 20 meters with a rope at a 30o angle and in doing so applies a force of 10 Newtons. How much work does he do?

4. Force on an incline
W = FIId
(200 N x 10 m) = 2000J
50 N x 10mCos(180o) = -500J
-500 J is the work done against friction.
Notice the angle is 180o between the FF and distance travelled!
500 J of Bobs 2000 J of energy is put into fighting friction.
Lets say Bob pushes a crate up a 40o incline with a force of 200 N for 10 meters. The force of friction is 50 N. How much work is done against friction?

5. Gravitational Potential Energy (PEG)
Gravitational Potential Energy: An object has the ability to do work when raised to a certain height with gravity.
How does our PEG on this floor compare to Mr. Trombetta’s PEG?
We have more since we are higher up!
PEG = mgh

6. Kinetic Energy
Kinetic Energy: An object in motion has the ability to do work (Energy in motion).
If I ask you to put a lot of energy into a throw. What is going to be the result?
More speed = More energy
Lets say I drop a basketball and a golf ball from the ceiling. Which will have more energy?
The larger one, it has more mass
KE = (1/2)mv2

7. Energy of a 3.6 kg bowling ball
Using a timer, determine how long it takes the ball to fall and then determine the balls height and final speed. What is KE max and PEG max?
About 3 sec….