1. Do Now:
1. Calculate the distance between two 75 kg individuals that have a gravitational attraction of 8.34 x 10-7N.

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

3. Demos Pulling Jeff around the room. Jeff lifting up his desk
Jeff holding his desk
Jeff’s desk sitting there without Jeff
Work done
No Work

4. Work Work: Energy transferred by a force. Energy: Ability to do work
W = FIId Cosθ Unit: Joule (J)
Energy or Work is a scalar quantity
Dakota pulls Alicia 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?

5. NO! In order for work to be done on the box it must MOVE!
More on Work…
A person is trying to push a heavy box across a classroom floor, but the box does not move. Is work being done on the box?
NO! In order for work to be done on the box it must MOVE!

6. Doing work on an incline
30m
35N
A box is pulled up a 30 meter long inclined plane at an angle of 30º with a force of 35 Newtons at constant speed. Calculate the work done by the 35 N force in moving the box.
WORK IS DONE IN THE DIRECTION OF THE NET FORCE!!!
If distance and Force are Parallel then we are O.K!!!

7. Station 1
15N
40°
A wagon is pulled a horizontal distance of 5 meters with a force of 15 Newtons at an angle of 40º above the horizontal. How much work is done?

8. Station 2
A 50kg crate full of twinkies is pushed 30 meters up a 20o incline with a constant speed and force of 200N. What is the work due to friction? (Hint: Sketch)

9. Summary
What is the definition for work? What is the exact equation for work? What are the units? The Whole World is Made of Energy