1. What is friction?
2. Which surface produces the most friction?
3. What is used to reduce friction in machines?
4. Which type of friction acts when an object is moving?
5. Which friction is greater?
6. What reduces friction in ball bearings?
7. Which force enables us to walk?
8. What is streamlined shape used for?
9. What is the friction in fluids called?
10. Why are soles of shoes grooved?
11. What type of friction is experienced by a car tire on a road?
12. What is a common disadvantage of friction?
13. Why do lubricants reduce friction?
14. In which of these is fluid friction encountered?
15. Which of the following experiences least friction?
16. Which factor does not affect friction?
17. Which shape reduces air resistance?
18. Why do parachutes work effectively?
19. What is one useful effect of friction?
20. Which of the following materials is used to reduce friction in engines?
21. What will happen if friction suddenly disappears while walking?
22. What kind of friction is experienced when skydiving?
23. Which one is used in machines to convert sliding friction to rolling friction?
24. What kind of surfaces increase friction?
25. What is the frictional force experienced before movement called?
26. Why do gymnasts use chalk powder?
27. What causes friction between two objects?
28. What does air resistance depend on?
29. What happens to friction when pressure increases?
30. Why is oil applied to machine parts?
31. Why do matchsticks light when struck?
32. Why is it hard to move a heavy box on the floor?
33. What type of friction acts between a book resting on a table?
34. Why are wheels used in trolleys?
35. Which type of friction is the least?
36. What increases fluid friction?
37. What does excessive friction cause in machines?
38. Which of these reduces friction in car engines?
39. Which of the following uses friction for its function?
40. What is friction between water and a swimmer called?