1. Machines 1. What is Work?

2. You probably do many kinds of work
You may do work for school

3. You may do work around your house such as mowing the lawn
You may work at a job

4. But these things are not what scientists call work
For scientists, work has a special meaning

5. the use of force to move an object
Vocabulary:
work
the use of force to move an object
W = F  D

6. In order for an action to be work
the force used must be in the same direction as the motion

7. The golfer applies force on the club, which causes the club to move
The club applies force on the ball which causes the ball to move

8. you would not be doing work
If you pushed as hard as you could against a big pig and the pig did not move
you would not be doing work

9. Work only happens when an object moves

10. Lifting a fish out of water is work
When you lift the fish you use a force to move the fish

11. You pull upward on the fish
and the fish moves upward

12. Holding a fish to show it off is not work
But when you carry the fish you are using force to keep the fish from falling

13. The force is an upward force
But the fish is moving forward as you (or the bear) walk

14. Since the force and the motion are not in the same direction
So no work is being done

15. In this unit you will learn more about work
and how people make work easier to do