# Friction Test 3

Total Questions:25 Total Time: 45 Min

Remaining:

## Questions 1 of 25

Question:A uniform rope of length l lies on a table. If the coefficient of friction is $$\mu$$, then the maximum length $${l_1}$$ of the part of this rope which can overhang from the edge of the table without sliding down is

$$\frac{l}{\mu }$$

$$\frac{l}{{\mu + l}}$$

$$\frac{{\mu l}}{{1+ \mu }}$$

$$\frac{{\mu l}}{{\mu - 1}}$$

## Questions 2 of 25

Question:Which of the following statements is not true

The coefficient of friction between two surfaces increases as the surface in contact are made rough

The force of friction acts in a direction opposite to the applied force

Rolling friction is greater than sliding friction

The coefficient of friction between wood and wood is less than 1

## Questions 3 of 25

Question:A block of 1 kg is stopped against a wall by applying a force F perpendicular to the wall. If $$\mu = 0.2$$ then minimum value of F will be

980 N

49 N

98 N

490 N

## Questions 4 of 25

Question:A heavy uniform chain lies on a horizontal table-top. If the coefficient of friction between the chain and table surface is 0.25, then the maximum fraction of length of the chain, that can hang over one edge of the table is

20%

25%

35%

15%

## Questions 5 of 25

Question:A horizontal force of 10 N is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is 0.2. the weight of the block is

2 N

20 N

50 N

100 N

## Questions 6 of 25

Question:The coefficient of static friction, $${\mu _s},$$ between block A of mass 2 kg and the table as shown in the figure is 0.2. What would be the maximum mass value of block B so that the two blocks do not move? The string and the pulley are assumed to be smooth and massless. $$(g = 10\,m/{s^2})$$

2.0 kg

4.0 kg

0.2 kg

0.4 kg

## Questions 7 of 25

Question:If mass of $$A = 10\,\,kg$$, coefficient of static friction = 0.2, coefficient of kinetic friction = 0.2. Then mass of B to start motion is

2 kg

2.2 kg

4.8 kg

200 gm

## Questions 8 of 25

Question:A uniform metal chain is placed on a rough table such that one end of chain hangs down over the edge of the table. When one-third of its length hangs over the edge, the chain starts sliding. Then, the coefficient of static friction is

$$\frac{3}{4}$$

$$\frac{1}{4}$$

$$\frac{2}{3}$$

$$\frac{1}{2}$$

## Questions 9 of 25

Question:A motorcyclist of mass m is to negotiate a curve of radius r with a speed v. The minimum value of the coefficient of friction so that this negotiation may take place safely, is

$${v^2}rg$$

$$\frac{{{v^2}}}{{gr}}$$

$$\frac{{gr}}{{{v^2}}}$$

$$\frac{g}{{{v^2}r}}$$

## Questions 10 of 25

Question:On a rough horizontal surface, a body of mass 2 kg is given a velocity of 10 m/s. If the coefficient of friction is 0.2 and $$g = 10\,m/{s^2}$$, the body will stop after covering a distance of

10 m

25 m

50 m

250 m

## Questions 11 of 25

Question:A block of mass 50 kg can slide on a rough horizontal surface. The coefficient of friction between the block and the surface is 0.6. The least force of pull acting at an angle of 30Â° to the upward drawn vertical which causes the block to just slide is

29.43 N

219.6 N

21.96 N

294.3 N

## Questions 12 of 25

Question:A body of 10 kg is acted by a force of 129.4 N if $$g = 9.8\,m/{\sec ^2}$$. The acceleration of the block is $$10\,m/{s^2}$$. What is the coefficient of kinetic friction

0.03

0.01

0.3

0.25

## Questions 13 of 25

Question:Assuming the coefficient of friction between the road and tyres of a car to be 0.5, the maximum speed with which the car can move round a curve of 40.0 m radius without slipping, if the road is unbanked, should be

25 m/s

19 m/s

14 m/s

11 m/s

## Questions 14 of 25

Question:A horizontal force of 129.4 N is applied on a 10 kg block which rests on a horizontal surface. If the coefficient of friction is 0.3, the acceleration should be

$$9.8\,m/{s^2}$$

$$10\,m/{s^2}$$

$$12.6\,m/{s^2}$$

$$19.6\,m/{s^2}$$

## Questions 15 of 25

Question:A 60 kg weight is dragged on a horizontal surface by a rope upto 2 metres. If coefficient of friction is $$\mu = 0.5$$, the angle of rope with the surface is 60$$^0$$ and $$g = 9.8\,m/{\sec ^2}$$, then work done is

294 joules

315 joules

588 joules

197 joules

## Questions 16 of 25

Question:A car having a mass of 1000 kg is moving at a speed of 30 metres/sec. Brakes are applied to bring the car to rest. If the frictional force between the tyres and the road surface is 5000 newtons, the car will come to rest in

5 seconds

10 seconds

12 seconds

6 seconds

## Questions 17 of 25

Question:If $${\mu _s},\,{\mu _k}$$ and $${\mu _r}$$ are coefficients of static friction, sliding friction and rolling friction, then

$${\mu _s} < {\mu _k} < {\mu _r}$$

$${\mu _k} < {\mu _r} < {\mu _s}$$

$${\mu _r} < {\mu _k} < {\mu _s}$$

$${\mu _r} = {\mu _k} = {\mu _s}$$

## Questions 18 of 25

Question:A body of mass 5kg rests on a rough horizontal surface of coefficient of friction 0.2. The body is pulled through a distance of 10m by a horizontal force of 25 N. The kinetic energy acquired by it is (g = 10 ms$$^{\rm{2}}$$)

330 J

150 J

100 J

50 J

## Questions 19 of 25

Question:Starting from rest, a body slides down a 45Â° inclined plane in twice the time it takes to slide down the same distance in the absence of friction. The coefficient of friction between the body and the inclined plane is

0.33

0.25

0.75

0.8

## Questions 20 of 25

Question:The coefficient of friction between a body and the surface of an inclined plane at 45$$^\circ$$ is 0.5. If $$g = 9.8\,m/{s^2}$$, the acceleration of the body downwards in $$m/{s^2}$$ is

$$\frac{{4.9}}{{\sqrt 2 }}$$

$$4.9\sqrt 2$$

$$19.6\sqrt 2$$

4.9

## Questions 21 of 25

Question:A box is placed on an inclined plane and has to be pushed down. The angle of inclination is

Equal to angle of friction

More than angle of friction

Equal to angle of repose

Less than angle of repose

## Questions 22 of 25

Question:A force of 750 N is applied to a block of mass 102 kg to prevent it from sliding on a plane with an inclination angle 30$$^\circ$$ with the horizontal. If the coefficients of static friction and kinetic friction between the block and the plane are 0.4 and 0.3 respectively, then the frictional force acting on the block is

750 N

500 N

345 N

250 N

## Questions 23 of 25

Question:A block rests on a rough inclined plane making an angle of $${30^o}$$ with the horizontal. The coefficient of static friction between the block and the plane is 0.8. If the frictional force on the block is 10 N, the mass of the block (in kg) is (take $$g = 10\,\,m/{s^2})$$

2

4

1.6

2.5

## Questions 24 of 25

Question:A body takes time t to reach the bottom of an inclined plane of angle q with the horizontal. If the plane is made rough, time taken now is 2t. The coefficient of friction of the rough surface is

$$\frac{3}{4}\tan \theta$$

$$\frac{2}{3}\tan \theta$$

$$\frac{1}{4}\tan \theta$$

$$\frac{1}{2}\tan \theta$$

## Questions 25 of 25

Question:A block is kept on an inclined plane of inclination q of length l. The velocity of particle at the bottom of inclined is (the coefficient of friction is$$\mu$$)

$$\sqrt {2gl(\mu \cos \theta - \sin \theta )}$$
$$\sqrt {2gl(\sin \theta - \mu \cos \theta )}$$
$$\sqrt {2gl(\sin \theta + \mu \cos \theta )}$$
$$\sqrt {2gl(\cos \theta + \mu \sin \theta )}$$