1. Ch 6 Test: Controlling Heat Transfer
Please remove hats and hoods

2. Ch 7 Simple Machines Science 14 and 10-4 with Mrs M
Please remove your hats

3. 7.1 Many types of Energy
We have already talked about thermal energy or heat
Kinetic energy = energy of motion (recall temperature is the average of kinetic energy)
What about the energy used in machines?

4. Many types of energy
Energy is the ability to do work

5. Work = Force x distance W = F x d
Work is a form of energy measured in Newton meter (Nm) or Joules (J)
Work is defined as a force applied over a distance

6. Which requires more effort or force, a short/steep or a long/gradual ramp?

7. W = F x d
A force of 20 N is required to lift a box. The box is lifted from the floor to a shelf that is 2m high. What is the amount of work done?
W = F x d
W = 20 x 2
W = 40 Nm

8. W = F x d
Pushing a wheelbarrow takes 8000 Nm of work. How much force was needed to move it 25 m?

9. Simple Machines Simple machines have one movement
The movement of an inclined plane/ramp is a slide.
A ramp is an old simple machine

10. Work requires a FORCE input over a DISTANCE
Work being done by pedaling force uphill
No Work

11. Pushing against a wall is NOT work… because it’s not moving!

12. Quick Quiz #5
Open book
Individual

13. Levers
Lever: a rigid bar resting on a pivot, used to help move a heavy load/weight
Fulcrum= pivot point
Load= weight to be moved
Effort= force applied

14. Levers
Fulcrum in middle 1st class Load/Weight in the middle 2nd class Effort/Force in the middle 3rd class

15. 1st class Effort, Fulcrum, Load

16. 1st class levers

17. 1st class Fulcrum in the middle

18. 2nd Class Lever Load or Weight in the middle

19. 2nd class levers

20. 2nd class Load or weight in the middle

21. 3rd Class Levers Effort or Force in the middle

22. 3rd class levers

23. 3rd class lever Effort in the middle

24. FLE 123

25. Why should a heavier person sit closer to the fulcrum on a teeter totter?

26. Center of mass Girl’s Work = Boy’s Work Girl’s Force x girl’s distance = Boy’s Force x boy’s distance Weight(girl)x d = Weight(boy)x d

27. Weight(girl)x d = Weight(boy)x d
The little girl’s weight is 133 N and sits 0.5m from the middle of the teeter totter. How far away does the boy sit if he weighs 265 N?
Weight(girl)x d = Weight(boy)x d
133 x 0.5 = 265 x d
(133x0.5)/265 = d