1. Lesson 8

2. Work Work – when a force acts on an object and it moves some distance. WORK = Force (N) x Distance (m) L 8

3. WORK Alice pulls a sled with a force of 12 N. She pulls the sled through a distance of 5 m. How much work does Alice do on the sled? L 8

4. WORK Work = force x distance Work = 12 N x 5 m = 60 N-m L 8

5. WORK Michael lifts his book bag, which weighs 25 N, from the floor to a desktop that is 0.80 m above the floor. How much work does Michael do on the bag? L 8

6. WORK Force x Distance = WORK 25 N x 0.80 m = 20.0 N-m L 8

7. Inquiry 8.1 Calculating the Work Done on Different Surfaces L 8

8. 1. What force are you working against when you lift a backpack? L 8.1b

9. 2. In which of the following cases is work, as defined by scientists, being done? A. Someone tries to move a piano, but the piano won’t budge. L 8.1b

10. B. A tow truck is pulling a car slowly along the street. L8.1b

11. C. A student is studying for a mathematics exam. L 8-1b

12. D. A student is pushing a grocery cart around a store. L 8.1b

13. E. Another student is standing in line holding a 12-N bag of potatoes. L 8.1b

14. F. A student pushes against the school building. L 8.1b

15. Lesson 8

16. Question – Lesson 8 Is the motor capable of doing enough work to lift the sled to a distance of.10 m?

17. Lesson 8 If _________________,then __________ because _________________.

18. Lesson 8 Materials 1. 2. 3.

19. Lesson 8

20. Lifting a Load 1. Motor force with three batteries in series: _________________ 2. Work done by a motor when it lifts a load 10.0 cm. (0.10 m) Work = _______ x _______ = ______ L 8-2

21. 3. Weight of six washers:______________ 4.Work to raise six washers: Work = ______ x _______ = _______ 5. Your estimate of sled’s weight: _______ 6.Sled’s actual weight: _________ L 8-2

22. 7.Work to lift sled 10.0 cm. (0.10 m): Work = _________ x ______ = _______ L 8-2

23. Lesson 8

24. Vocabulary – Lesson 8 What happens when an object changes its position by moving in the direction of the force that is being applied is (62) work. Work = force x distance (w = fd) Work involves a force applied across a distance. The metric unit of work is the (63) newton-meter (N-m). A newton-meter is also a (64) joule (J). James Joule – described the relationship between work and energy. L8

25. Vocabulary – Lesson 8 A force is applied to lift the sled. This is the (65) effort force. The distance the sled moves is the (66) effort distance.

26. Vocabulary – Lesson 8 Electric current flows through the wire. The unit used to describe how much electric current flows through a wire is the (67) ampere (amp). Andre Ampere The electric potential of a battery is measured in (68) volts. Alessandra Volta