Friction Test 2

Total Questions:25 Total Time: 45 Min

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Questions 1 of 25

Question:In the figure shown, a block of weight 10 N resting on a horizontal surface. The coefficient of static friction between the block and the surface \({\mu _s} = 0.4\). A force of 3.5 N will keep the block in uniform motion, once it has been set in motion. A horizontal force of 3 N is applied to the block, then the block will

Answers Choices:

Move over the surface with constant velocity

Move having accelerated motion over the surface

Not move

First it will move with a constant velocity for some time and then will have accelerated motion

Questions 2 of 25

Question:Two masses A and B of 10 kg and 5 kg respectively are connected with a string passing over a frictionless pulley fixed at the corner of a table as shown. The coefficient of static friction of A with table is 0.2. The minimum mass of C that may be placed on A to prevent it from moving is

Answers Choices:

15 kg

10 kg

5 kg

12 kg

Questions 3 of 25

Question:The limiting friction is

Answers Choices:

Always greater than the dynamic friction

Always less than the dynamic friction

Equal to the dynamic friction

Sometimes greater and sometimes less than the dynamic friction

Questions 4 of 25

Question:Which is a suitable method to decrease friction

Answers Choices:

Ball and bearings

Lubrication

Polishing

All the above

Questions 5 of 25

Question:A box is lying on an inclined plane what is the coefficient of static friction if the box starts sliding when an angle of inclination is 60 o

Answers Choices:

1.17

1.73

2.73

1.68

Questions 6 of 25

Question:A block of mass 2 kg is kept on the floor. The coefficient of static friction is 0.4. If a force F of 2.5 Newtons is applied on the block as shown in the figure, the frictional force between the block and the floor will be

Answers Choices:

2.5 N

5 N

7.84 N

10 N

Questions 7 of 25

Question:Which one of the following is not used to reduce friction

Answers Choices:

Oil

Ball bearings

Sand

Graphite

Questions 8 of 25

Question:If a ladder weighing 250N is placed against a smooth vertical wall having coefficient of friction between it and floor is 0.3, then what is the maximum force of friction available at the point of contact between the ladder and the floor[AIIMS 2002]

Answers Choices:

75 N

50 N

35 N

25 N

Questions 9 of 25

Question:A body of mass 2 kg is kept by pressing to a vertical wall by a force of 100 N. The coefficient of friction between wall and body is 0.3. Then the frictional force is equal to

Answers Choices:

6 N

20 N

600 N

700 N

Questions 10 of 25

Question:Two carts of masses 200 kg and 300 kg on horizontal rails are pushed apart. Suppose the coefficient of friction between the carts and the rails are same. If the 200 kg cart travels a distance of 36 m and stops, then the distance travelled by the cart weighing 300 kg is

Answers Choices:

32 m

24 m

16 m

12 m

Questions 11 of 25

Question:A body B lies on a smooth horizontal table and another body A is placed on B. The coefficient of friction between A and B is \(\mu \). What acceleration given to B will cause slipping to occur between A and B

Answers Choices:

\(\mu g\)

\(g/\mu \)

\(\mu /g\)

\(\sqrt {\mu g} \)

Questions 12 of 25

Question:A 60 kg body is pushed with just enough force to start it moving across a floor and the same force continues to act afterwards. The coefficient of static friction and sliding friction are 0.5 and 0.4 respectively. The acceleration of the body is

Answers Choices:

\(6\,m/{s^2}\)

\(4.9\,m/{s^2}\)

\(3.92\,m/{s^2}\)

\(1\,m/{s^2}\)

Questions 13 of 25

Question:A car turns a corner on a slippery road at a constant speed of \(10\,m/s\). If the coefficient of friction is 0.5, the minimum radius of the arc in meter in which the car turns is

Answers Choices:

20

10

5

4

Questions 14 of 25

Question:When a body is moving on a surface, the force of friction is called

Answers Choices:

Static friction

Dynamic friction

Limiting friction

Rolling friction

Questions 15 of 25

Question:A block of mass 10 kg is placed on a rough horizontal surface having coefficient of friction \(\mu \) = 0.5. If a horizontal force of 100 N is acting on it, then acceleration of the block will be

Answers Choices:

0.5 m/s\(^{\rm{2}}\)

5 m/s\(^{\rm{2}}\)

10 m/s\(^{\rm{2}}\)

15 m/s\(^{\rm{2}}\)

Questions 16 of 25

Question:It is easier to roll a barrel than pull it along the road. This statement is

Answers Choices:

FALSE

TRUE

Uncertain

Not possible

Questions 17 of 25

Question:A marble block of mass 2 kg lying on ice when given a velocity of 6 m/s is stopped by friction in 10s. Then the coefficient of friction is

Answers Choices:

0.01

0.02

0.03

0.06

Questions 18 of 25

Question:When a body is placed on a rough plane inclined at an angle \(\theta \) to the horizontal, its acceleration is

Answers Choices:

\(g(\sin \theta - \cos \theta )\)

\(g(\sin \theta - \mu \cos \theta )\)

\(g(\mu \sin \theta 1 - \cos \theta )\)

\(g\mu (\sin \theta - \cos \theta )\)

Questions 19 of 25

Question:A block is at rest on an inclined plane making an angle \(\alpha \) with the horizontal. As the angle \(\alpha \) of the incline is increased, the block starts slipping when the angle of inclination becomes \(\theta \). The coefficient of static friction between the block and the surface of the inclined plane is or A body starts sliding down at an angle \(\theta \) to horizontal. Then coefficient of friction is equal to

Answers Choices:

\(\sin \theta \)

\(\cos \theta \)

\(\tan \theta \)

Independent of \(\theta \)

Questions 20 of 25

Question:A given object takes n times as much time to slide down a 45\(^\circ \) rough incline as it takes to slide down a perfectly smooth 45\(^\circ \) incline. The coefficient of kinetic friction between the object and the incline is given by

Answers Choices:

\(\left( {1 - \frac{1}{{{n^2}}}} \right)\)

\(\frac{1}{{1 - {n^2}}}\)

\(\sqrt {\left( {1 - \frac{1}{{{n^2}}}} \right)} \)

\(\sqrt {\frac{1}{{1 - {n^2}}}} \)

Questions 21 of 25

Question:The force required just to move a body up an inclined plane is double the force required just to prevent the body sliding down. If the coefficient of friction is 0.25, the angle of inclination of the plane is

Answers Choices:

36.8\(^\circ \)

45\(^\circ \)

30\(^\circ \)

42.6\(^\circ \)

Questions 22 of 25

Question:A block of mass 10 kg is placed on an inclined plane. When the angle of inclination is 30\(^0\), the block just begins to slide down the plane. The force of static friction is

Answers Choices:

10 kg wt

89 kg w

49 kg wt

5 kg wt

Questions 23 of 25

Question:A body of 5 kg weight kept on a rough inclined plane of angle 30\(^0\) starts sliding with a constant velocity. Then the coefficient of friction is (assume g = 10 m/s\(^2\))

Answers Choices:

\(1/\sqrt 3 \)

\(2/\sqrt 3 \)

\(\sqrt 3 \)

\(2\sqrt 3 \)

Questions 24 of 25

Question:300 Joule of work is done in sliding up a 2 kg block on an inclined plane to a height of 10 metres. Taking value of acceleration due to gravity ‘g’ to be 10 m/s\(^2\), work done against friction is

Answers Choices:

100 J

200 J

300 J

Zero

Questions 25 of 25

Question:A 2 kg mass starts from rest on an inclined smooth surface with inclination 30\(^0\) and length 2 m. How much will it travel before coming to rest on a frictional surface with frictional coefficient of 0.25

Answers Choices:

4 m

6 m

8 m

2 m