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The force of friction depends upon

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Important Questions on Friction

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Physics>Mechanics>Friction>Dynamic Friction

Friction can be reduced by changing from

EASY

Physics>Mechanics>Friction>Dynamic Friction

A thin motorcyclist rides with sufficient speed in the vertical plane inside a hollow sphere of diameter

20 m

to prevent himself from sliding down. If the coefficient of friction is

0.5,

then what is the minimum speed of the motor cyclist? (use

g = 10 m s^{- 2}

)

EASY

Physics>Mechanics>Friction>Dynamic Friction

Frictional forces act in a direction

EASY

Physics>Mechanics>Friction>Dynamic Friction

Which of the following is a self adjusting force?

EASY

Physics>Mechanics>Friction>Dynamic Friction

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

EASY

Physics>Mechanics>Friction>Dynamic Friction

Which one of the following statements is incorrect?

EASY

Physics>Mechanics>Friction>Dynamic Friction

Which of the following surface in contact has maximum coefficient of friction

(μ)

EASY

Physics>Mechanics>Friction>Dynamic Friction

A rectangular film of liquid is extended from

(4 cm \times 2 cm)

(5 cm \times 4 cm)

. If the work done is

3 \times 10^{- 4} J

, the value of the surface tension of the liquid is

EASY

Physics>Mechanics>Friction>Dynamic Friction

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>Dynamic Friction

Meena applies the front brakes while riding on her bicycle along a flat road. The force that slows her bicycle is provided by the

MEDIUM

Physics>Mechanics>Friction>Dynamic Friction

A car is negotiating a curved road of radius

R

. The road is banked at an angle

θ

. The coefficient of friction between the tyres of the car and the road is

μ_{s}

. The maximum safe velocity on this road is:

EASY

Physics>Mechanics>Friction>Dynamic Friction

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 :

HARD

Physics>Mechanics>Friction>Dynamic Friction

Assume that a drop of a liquid evaporates by a decrease in its surface energy so that its temperature remains unchanged. The minimum radius of the drop for this to be possible is. (The surface tension is

T

, the density of the liquid is

ρ

and

L

is its latent heat of vaporisation.)

EASY

Physics>Mechanics>Friction>Dynamic Friction

A block of mass

10 kg

starts sliding on a surface with an initial velocity of

9.8 {ms}^{- 1}

. The coefficient of friction between the surface and block is

0.5

. The distance covered by the block before coming to rest is :[use

g = 9.8 {ms}^{- 2}

]

MEDIUM

Physics>Mechanics>Friction>Dynamic Friction

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>Dynamic Friction

When one end of the capillary is dipped in water, the height of the water column is

h

. The upward force of

105 dyne

due to surface tension is balanced by the force due to the weight of the water column. The inner circumference of the capillary is
(Surface tension of water

= 7 \times 10^{- 2} N m^{- 1})

MEDIUM

Physics>Mechanics>Friction>Dynamic Friction

The following observations were taken for determining surface tension

T

of water by capillary method:

diameter of capillary,

D = 1.25 \times 10^{- 2} m

rise of water,

h = 1.45 \times 10^{- 2} m

Using

g = 9.80 m s^{- 2}

and the simplified relation

T = \frac{r h g}{2} \times 10^{3} N m^{- 1}

the possible error in surface tension is closest to:

EASY

Physics>Mechanics>Friction>Dynamic Friction

A block placed on the horizontal is pushed momentarily with initial velocity

v

. The coefficient of friction between the block and surface is

μ

. Block will come to rest after a time

t

equal to (

g =

acceleration due to gravity)

EASY

Physics>Mechanics>Friction>Dynamic Friction

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>Dynamic Friction

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:

The force of friction depends upon

Important Questions on Friction

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