Friction Section Review

1. Friction Section Review

2. 1. What is Friction? • A. a force creating motion • B. a force of motion • C. a force opposing motion • D. velocity

3. ANSWER • C. A force opposing motion

4. 2. What are two factors that determine the amount of friction? • A. the force and roughness of the surfaces • B. hills and valleys and the roughness of the surfaces • C. the force and how much surface comes n contact • D. the force and weight exerted on the surfaces.

5. ANSWER • A. the force and roughness of the surfaces.

6. 3. What kind of friction takes place between moving surfaces? • a. kinetic • b. static • c. smooth • d. rough

7. ANSWER • A. Kinetic

8. 4. What type of kinetic friction is used to write with a pencil? • a. static • b. sliding • c. rolling • d. smooth

9. Answer • B. sliding

10. 5. Which of these is opposed by kinetic friction? • A. a book sitting on a table • B. a cat standing in the yard • C. a child leaning on a building • D. a box sliding on the floor.

11. ANSWER • D. a box sliding on the floor. Kinetic friction occurs when two objects are moving in opposite directions of each other.

12. 6.Use the figure to help answer the question: Look at Figure A below. Why does the block not move? • a. no force applied • b. force of friction • c. surface friction • d. kinetic friction

13. ANSWER • A. No force is applied

14. 7. Use the figure to help answer the question: Look at Figure B below. The block does not move. What force keeps the block from moving? • a. rolling kinetic friction • b. sliding kinetic friction • c. static friction • d. kinetic friction

15. ANSWER • C. static friction

16. 8. In which of the following activities is friction helpful? • A. soil erosion • B. car tires moving a car forward • C. engine parts wearing out • D. holes developing in your socks

17. ANSWER • B. car tires moving your car forward.

18. 9. What would happen if you tried to walk without friction? • a. You would slip and fall. • b. You would get lost. • c. You would change direction. • d. You would go slower.

19. ANSWER • A. you would slip and fall

20. 10. How do lubricants affect friction? • a. increases friction • b. decreases friction • c. increases force • d. decreases force

21. ANSWER • B. decrease friction

22. 11. How does sand on an icy road keep cars from skidding? • a. It makes surfaces hotter • B. it makes surfaces smoother • C. it makes surface rougher • D. it makes surfaces nicer

23. ANSWER • C. it makes surfaces rougher

24. 12. Which of these is opposed by static friction? • A. a chair sliding on the floor • B. a pencil rolling on the table • C. a dog running in the yard • D. a worker pushing a non moving box

25. ANSWER • D. a worker pushing a non-moving box

26. 13. Why is it easy to slip when there is water on the floor? • A. the water is very wet • B. the water creates static friction • C. the water acts as a lubricant • D. the water creates hills and valleys on the floor

27. ANSWER • C. the water acts as a lubricant

28. 14. In which of the following is friction harmful? • A. brakes stopping a car • B. an eraser erasing • C. car engine parts wearing out • D. a person walking

29. ANSWER • C. car engine parts wearing out.

30. 15. Which would NOT be a way to reduce friction? • A. pouring sand on ice • B. lubricating with oil • C. using sandpaper • D. using ball bearings

31. ANSWER • A. pouring sand on ice.

32. 16. What would be the benefit of using snow tires on a car? • A. they reduce the amount of friction • B. they’re for snow……….duh • C. they increase friction • D. they create rolling kinetic friction

33. ANSWER • C. they increase friction

34. 17. What is one way to increase friction when sanding a piece of wood? • a. Press harder. • b. Freeze the wood. • c. Use oil. • d. Use ball bearings.

35. ANSWER • A. press harder.