Physics Worksheet: Friction & Inclined Plane
Level: Medium → Higher Difficulty
Topics: Normal reaction, static friction, limiting friction, inclined plane, angle of friction, angle of repose
Assume: , unless otherwise stated.
All questions have one correct answer.
Questions
1. A block of mass 5 kg rests on a horizontal rough surface. The coefficient of static friction is 0.4. A horizontal force of 12 N is applied. The frictional force on the block is:
A) 0 N
B) 8 N
C) 12 N
D) 20 N
2. A 10 kg block is placed on a horizontal surface with coefficient of static friction 0.5. The minimum horizontal force required to just start moving the block is:
A) 25 N
B) 40 N
C) 50 N
D) 100 N
3. A 4 kg block is pulled horizontally by a force of 15 N on a rough horizontal surface. If , the magnitude of friction acting on the block is:
A) 10 N
B) 15 N
C) 20 N
D) 0 N
4. A 20 kg block rests on a horizontal surface. A force of 60 N is applied at an angle 30∘ above the horizontal. If , the frictional force acting on the block is:
A) 60 N
B) 68 N
C) 102 N
D) 80 N
5. A 10 kg block is pulled by a force of 50 N at 37∘ above the horizontal. If , the block is:
(Take )
A) Just about to move
B) Moving with acceleration 1 m/s2
C) In equilibrium with friction 40 N
D) Moving with constant velocity
6. A 5 kg block is placed on a 30∘ rough incline. The coefficient of static friction is 0.4. The minimum force applied parallel upward along the plane to prevent the block from sliding down is:
A) 10 N
B) N
C) N
D) 25 N
7. A 10 kg block is placed on a 37∘ incline. If , the maximum static friction available is:
A) 30 N
B) 40 N
C) 50 N
D) 80 N
8. A 5 kg block is at rest on a 37∘ incline. If , the actual frictional force acting on it is:
A) 30 N
B) 37.5 N
C) 40 N
D) 50 N
9. A block is placed on an inclined plane of angle 30∘. The coefficient of static friction is 1/sqrt(3). The block is:
A) Definitely sliding downward
B) Definitely moving upward
C) Just at the point of slipping
D) In equilibrium with zero friction
10. A block of mass 8 kg is on a rough incline of 30∘. If , the minimum force applied parallel to the plane upward to prevent downward slipping is:
A) 4 N
B) N
C) N
D) 40 N
11. A 10 kg block is on a 37∘ incline. A force of 20N acts parallel upward along the plane. If , the frictional force is:
A) 20 N downward
B) 40 N upward
C) 40 N downward
D) 50 N downward
12. A block rests on a rough horizontal surface. At the instant when it is just about to move, the normal reaction is 100 N and the limiting friction is 60 N. The coefficient of static friction is:
A) 0.4
B) 0.5
C) 0.6
D) 1.67
13. The coefficient of static friction between a block and an inclined plane is 0.6. The angle of repose is approximately:
A) 20∘
B) 31∘
C) 37∘
D) 45∘
14. A block begins to slide down an inclined plane when the inclination is 45∘. The coefficient of static friction between the block and plane is:
A) 0.5
B) 5/7
C) 1
D) 1.4
15. A block is just about to slide on an inclined plane when the plane makes an angle 30∘ with the horizontal. The angle of friction is:
A) 15∘
B) 30∘
C) 45∘
D) 60∘
16. A 4 kg block is placed on a 53∘ rough incline. If , the maximum frictional force available is:
A) 18 N
B) 20 N
C) 24 N
D) 30 N
17. A 10 kg block is on a 37∘ incline. The coefficient of static friction is 0.5. A horizontal force F is applied to the block. What is the minimum value of F required to prevent the block from sliding down the incline?
Take .
A) 20 N
B) 25 N
C) 30 N
D) 40 N
18. A 5 kg block rests on a 37∘ incline with . A force F is applied up the incline. The minimum value of F required to prevent the block from sliding down is:
A) 5 N
B) 10 N
C) 15 N
D) 20 N
19. A 10 kg block is on a rough 37∘ incline. The coefficient of static friction is 0.5. A force of 80 N acts vertically upward on the block. The magnitude of friction required for equilibrium is:
A) 0 N
B) 10 N
C) 20 N
D) 40 N
Take .
20. A 10 kg block rests on a rough inclined plane. The angle of repose is 37∘. A force F is applied parallel to the plane upward. If the plane is inclined at 53∘, the minimum value of F required to keep the block in equilibrium is:
Take .
A) 20 N
B) 40 N
C) 50 N
D) 60 N
Answer Key
| Q | Answer | Q | Answer |
|---|---|---|---|
| 1 | C | 11 | C |
| 2 | C | 12 | C |
| 3 | B | 13 | B |
| 4 | A | 14 | C |
| 5 | A | 15 | B |
| 6 | B | 16 | C |
| 7 | C | 17 | B |
| 8 | C | 18 | C |
| 9 | C | 19 | B |
| 10 | C | 20 | B |
Key relations used:
where ϕ is the angle of friction and θR is the angle of repose.
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