1. Chapter 15 Work

2. How did humans thousands of years ago build such structures as the great pyramids of Egypt?

3. Work the force that is applied to move an object the direction the object moves must be in the same direction as the force applied if the object doesn’t move, then no work has been done

4. Examples Pushing against a wall -– no work has occurred because the object doesn’t move Lifting a bag of groceries –- work is done Carrying a bag of groceries – no work is being done

5. Examples Pushing a car Lifting a baby Carrying a baby Throwing a baseball Pushing against the floor Hammering a nail

6. How to Calculate Work Work = Force * Distance Units are defined as a joule (J) or a Newton*meter

8. Problem You lift a box that weighs 200 Newtons a distance of 0.5 meters. How much work is done?

9. Procedure Write the equation Figure out what is being asked – what are you solving for? Determine what information is given Plug & Chug – don’t forget the units!

10. Step One Write the equation Work = Force * Distance

11. Step Two Figure out what is being asked – what are you solving for? How much WORK is done?

12. Step Three Determine what information is given Box weighs (force) 200N Distance box moves = 0.5m

13. Step Four Plug & Chug – don’t forget the units! Work = (200N)(0.5m) = 100 N*m or = 100 J (joules)

14. You Try One! A 900N mountain climber scales a 100m cliff. How much work is done by the mountain climber?