1. Ch. 5 Work,
Energy, and Power

2. Bellwork 3/6/2018
Which student is doing work on the chair?

3. Work In physics, work has a very specific meaning.
In physics, work represents a measurable change in a system, caused by a force.

4. Formula for Work W = F x d (cos θ) Whenever θ = 90°…….. Then work = 0
Force is measured in Newtons (N)
Distance is measured in meters (m)
N x m = Joules

5. Requirements for work:
An object has to:
1) experience a force
AND……………………………….
2) Move a distance ( measured in meters) in the same direction as the applied force.

6. Work
If you push a box with a force of one newton for a distance of one meter, you have done exactly one joule of work.

7. A. Positive Work is done B. Negative Work is done C. No Work is done

8. Checkpoint
You have 5 minutes to research one example of positive, negative, and zero work being done.

9. Sample Problem
A 20.0 N tension force is applied to a suitcase to raise it 3.0 m above a platform by a conveyor belt. How much work is done on the suitcase?
Draw a free-body diagram to represent the scenario.

10. Only use the force acting on the suitcase
3.0 m
FTension
= 20.0 N
FGravity
Only use the force acting on the suitcase
W = F x d
W = 20.0 N x 3.0 m
W = 6.0 x 101J

11. Classwork
Page 163 #’a 1-6 (except #4)