EASY

Earn 100

Draw free body diagram of $3 kg$ block.

Important Questions on Friction

HARD

Physics>Mechanics>Friction>Multi-Block Problems

A block of mass

100 kg

attached to a massless rope and the second end of the rope is pulled up by

2

men along a rough inclined plane of coefficient of friction

0.2

inclined at

37 °

with the horizontal. If they exert their maximum force for the block to just start moving up, the force exerted by each of them is, (Acceleration due to gravity

= 10 m s^{- 2}, \tan 37 ° ≃ 0.75

)

EASY

Physics>Mechanics>Friction>Multi-Block Problems

Given in the figure are two blocks

A

and

B

of weight

20 N

and

100 N

, respectively. These are being pressed against a wall by a force

F

and kept in equilibrium as shown. If the coefficient of friction between the blocks is

0.1

and between block

B

and the wall is

0.15

, the frictional force applied by the wall on block

B

is:

MEDIUM

Physics>Mechanics>Friction>Multi-Block Problems

A block of mass $5 kg$ is kept against an accelerating wedge with a wedge angle of $45 °$ to the horizontal. The co-efficient of friction between the block and the wedge is $μ = 0.4$ . What is the minimum absolute value of the acceleration of the wedge to keep the block steady. Assume $g = 10 m s^{- 2}$

Question Image

EASY

Physics>Mechanics>Friction>Multi-Block Problems

A block rests on a rough inclined plane making an angle of

30 °

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 is

(g = 10 m s^{- 2})

EASY

Physics>Mechanics>Friction>Multi-Block Problems

A block A of mass 4 kg is placed on another block B of mass 5 kg, and the block B rests on a smooth horizontal table. If the minimum force that can be applied on A so that both the blocks move together is 12 N, the maximum force that can be applied on B for the blocks to move together will be :

EASY

Physics>Mechanics>Friction>Multi-Block Problems

A block is released from rest on a

45 °

smooth incline and slide a distance

d

. The time taken to slide the same distance is

n

times as much to slide on a

45 °

rough incline than on the smooth incline. The coefficients of friction for the rough incline is

MEDIUM

Physics>Mechanics>Friction>Multi-Block Problems

A block of mass $5 kg$ resting on a horizontal surface is connected by a cord, passing over a light frictionless pulley to a hanging block of mass $5 kg$ . The coefficient of kinetic friction between the block and the surface is $0.5$ . Tension in the cord is $(g = 9.8 m s^{- 2})$

Question Image

EASY

Physics>Mechanics>Friction>Multi-Block Problems

Which one of the following statements is incorrect?

MEDIUM

Physics>Mechanics>Friction>Multi-Block Problems

A heavy box is to be dragged along a rough horizontal floor. To do so, the person

A

pushes it at an angle

30 °

from the horizontal and requires a minimum force

F_{A}

, while the person

B

pulls the box at an angle

60 °

from the horizontal and needs minimum force

F_{B}

. If the coefficient of friction between the box and the floor is

\frac{\sqrt{3}}{5}

, the ratio

\frac{F_{A}}{F_{B}}

HARD

Physics>Mechanics>Friction>Multi-Block Problems

A system consists of three masses

m_{1}, m_{2}

and

m_{3}

connected by a string passing over a pulley

P .

The mass

m_{3}

hangs freely and

m_{2}

and

m_{1}

are on a rough horizontal table (the coefficient of friction

= μ) .

The pulley is frictionless and of negligible mass. The downward acceleration of mass

m_{3}

is: (Assume

m_{1} = m_{2} = m_{3} = m)

MEDIUM

Physics>Mechanics>Friction>Multi-Block Problems

A uniform chain of length

L

is lying partly on a table, the remaining part hanging down from the edge of the table. If the coefficient of friction between the chain and the table is

0.5,

what is the minimum length of the chain that should lie on the table, to prevent the chain from slipping down to the ground?

MEDIUM

Physics>Mechanics>Friction>Multi-Block Problems

A plank with a box on it at one end is gradually raised about the other end. As the angle of inclination with the horizontal reaches

30 °

, the box starts to slip and slides

4.0 m

down the plank in

4.0 s

. The coefficients of static and kinetic friction between the box and the plank will be, respectively:
Question Image

EASY

Physics>Mechanics>Friction>Multi-Block Problems

The coefficient of static friction between a wooden block of mass

0.5 kg

and a vertical rough wall is

0.2 .

The magnitude of the horizontal force that should be applied on the block to keep it adhere to the wall will be______

N

⌈g = 10 m s^{- 2}]

EASY

Physics>Mechanics>Friction>Multi-Block Problems

A body of mass

2 kg

is kept by pressing to a vertical wall by a force of

100 N

. The friction between wall and body is

0.3

. Then the frictional force is equal to

EASY

Physics>Mechanics>Friction>Multi-Block Problems

As shown in the figure, a block of mass $\sqrt{3} kg$ is kept on a horizontal rough surface of coefficient of friction $\frac{1}{3 \sqrt{3}}$ . The critical force to be applied on the vertical surface as shown at an angle $60 °$ with horizontal such that it does not move, will be $3 x$ . The value of $x$ will

$[g = 10 m s^{- 2}; \sin 60 ° = \frac{\sqrt{3}}{2}; \cos 60 ° = \frac{1}{2}]$

Question Image

HARD

Physics>Mechanics>Friction>Multi-Block Problems

A given object takes

n

times more time to slide down a

45^{o}

rough inclined plane as it takes to slide down a perfectly smooth

45^{o}

incline. The coefficient of kinetic friction between the object and the incline is:

EASY

Physics>Mechanics>Friction>Multi-Block Problems

Which of the following is a self adjusting force?

HARD

Physics>Mechanics>Friction>Multi-Block Problems

Put a uniform meter scale horizontally on your extended index fingers with the left one at

0.00 cm

and the right one at

90.00 cm

. When you attempt to move both the fingers slowly towards the center, initially only the left finger slips with respect to the scale and the right finger does not. After some distance, the left finger stops and the right one starts slipping. Then the right finger stops at a distance

x_{R}

from the center

(50.00 cm)

of the scale and the left one starts slipping again. This happens because of the difference in the frictional forces on the two fingers. If the coefficients of static and dynamic friction between the fingers and the scale are

0.40

and

0.32

, respectively, the value of

x_{R}

(in cm) is___________.

MEDIUM

Physics>Mechanics>Friction>Multi-Block Problems

A block

A

of mass

m_{1}

rests on a horizontal table. A light string connected to it passes over a frictionless pulley at the edge of table and from its other end another block

B

of mass

m_{2}

is suspended. The coefficient of kinetic friction between the block and the table is

μ_{k}

. When the block

B

is sliding on the table, the tension in string is:

EASY

Physics>Mechanics>Friction>Multi-Block Problems

A block kept on a rough inclined plane, as shown in the figure, remains at rest upto a maximum force

2 N

down the inclined plane. The maximum external force up the inclined plane that does not move the block is

10 N .

The coefficient of static friction between the block and the plane is: [Take

g = 10 m s^{- 2}

]

Draw free body diagram of 3kg block.

Important Questions on Friction

Learn and Prepare for any exam you want !

Draw free body diagram of $3 kg$ block.