Q451
Allen
FRICTION
MCQ
A box 'A' is lying on the horizontal floor of the compartment of a train running along horizontal rails from left to right. At time 't', it retards. Then the reaction R by the floor on the box is given best by:-
A.
B.
C.
D.
Q452
Allen
FRICTION
MCQ
A horizontal force F acts on the block of mass m and the block remains stationary, the value of friction force on the block is :-
A.
$\mu \mathrm{mg}$
B.
$\mu \mathrm{mg} - \mathrm{F}$
C.
F
D.
zero
Q453
Allen
FRICTION
MCQ
A block of mass 4 kg is placed on the floor. The coefficient of static friction is 0.4. Force of 8 N is applied on the block. The force of friction between the block and the floor is
A.
16 N
B.
8.0 N
C.
2.0 N
D.
zero
Q454
Allen
FRICTION
MCQ
A block of mass 3 kg is placed on a rough horizontal surface ( $\mu_{s} = 0.4$ ). A horizontal force of 8.7 N is applied on the block. The force of friction between the block and floor is :-
A.
8.7 N
B.
12N
C.
10N
D.
zero
Q455
Allen
FRICTION
MCQ
The frictional force of the air on a body of mass 0.5 kg, falling with an acceleration of $9.0 \, m/s^{2}$ , will be $(g = 10 \, m/sec^{2})$ :
A.
4.9 N
B.
0.5 N
C.
4.5 N
D.
5 N
Q456
Allen
FRICTION
MCQ
Consider a car moving on a straight road with a speed of 100 m/s. The distance at which car can be stopped is $[\mu_{k} = 0.5]$
A.
1000 m
B.
800 m
C.
400 m
D.
100 m
Q457
Allen
FRICTION
MCQ
A block of mass 10 kg is placed on a long trolley. The coefficient of friction between the block and trolley is 0.2. The trolley accelerates from rest with $0.5 \, m/s^{2}$ for 20 s. then what is the friction force?
A.
20 N
B.
100 N
C.
5 N
D.
10 N
Q458
Allen
FRICTION
MCQ
A 20 kg block is initially at rest. A 75 N force is required to set the block in motion. After the motion start, a force of 60 N is applied to keep the block moving with constant speed. The coefficient of static friction is :-
A.
0.6
B.
0.52
C.
0.44
D.
0.375
Q459
Allen
FRICTION
MCQ
A block of mass 1 kg lies on a horizontal surface in a truck. The coefficient of static friction between the block and the surface is 0.6. If the acceleration of the truck is $5 \, m/s^{2}$ , the frictional force acting on the block is :-
A.
5N
B.
6N
C.
10N
D.
15N
Q460
Allen
FRICTION
MCQ
A body of mass 10 kg lies on a rough horizontal surface. When a horizontal force of F newton acts on it, it gets an acceleration of $5m/s^{2}$ , and when the horizontal force is doubled, it gets an acceleration of $18m/s^{2}$ . The coefficient of friction between the body and the horizontal surface is:
A.
0.2
B.
0.4
C.
0.6
D.
0.8
Q461
Allen
FRICTION
MCQ
A horizontal force of 20 N is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and wall is 0.15. The weight of the block is :-
A.
$20\mathrm{N}$
B.
$3\mathrm{N}$
C.
$30\mathrm{N}$
D.
$0.3\mathrm{N}$
Q462
Allen
FRICTION
MCQ
A block of mass 1 kg. is pressed against a wall with a horizontal force of 25 N as shown in the figure. If the coefficient of friction between the wall and the block is 0.5 then the frictional force acting on the block will be $(g = 9.8 \, \text{m/s}^2)$ :-
A.
$9.8\mathrm{N}$
B.
$2.5\mathrm{N}$
C.
$12.5\mathrm{N}$
D.
$4.9\mathrm{N}$
Q463
Allen
FRICTION
MCQ
Adjoining figure shows two blocks A and B pushed against the wall with a force F. The wall is smooth but the surfaces in contact of A and B are rough. Which of the following is true for the system of blocks to be at rest against the wall?
A.
F should be more than the weight of A and B
B.
F should be equal to the weight of A and B
C.
F should be less than the weight of A and B
D.
system cannot be in equilibrium
Q464
Allen
FRICTION
MCQ
A force of 100N is applied on a block of mass 3 kg as shown in the figure. The coefficient of friction between the surface and the block is $\mu = \frac{1}{\sqrt{3}}$ . The frictional force acting on the block is :-
A.
15 N downwards
B.
25 N upwards
C.
20 N downwards
D.
30 N upwards
Q465
Allen
FRICTION
MCQ
In previous problem the acceleration of block is :-
A.
zero
B.
$10\mathrm{m / s^2}$ upwards
C.
$10\mathrm{m / s^2}$ downwards
D.
none of these
Q466
Allen
FRICTION
MCQ
The minimum value of force F required to keep the block stationary is :-
A.
$\frac{\mathrm{mg}}{\mu\cos\theta}$
B.
$\frac{\mathrm{mg}}{\sin\theta + \mu\cos\theta}$
C.
$\frac{\mathrm{mg}}{\sin\theta - \mu\cos\theta}$
D.
$\frac{\mathrm{mg}}{\mu\tan\theta}$
Q467
Allen
FRICTION
MCQ
In previous question the value of F for which friction force between the block and the wall is zero.
A.
mg
B.
$\frac{mg}{\sin\theta}$
C.
$\frac{mg}{\cos\theta}$
D.
$\frac{mg}{\tan\theta}$
Q468
Allen
FRICTION
MCQ
A block of mass 20 kg is acted upon by a force F = 30 N at an angle $53^{\circ}$ with the horizontal in downward direction as shown in diagram. The coefficient of friction between the block and the horizontal surface is 0.2. The friction force acting on the block by the ground is
$(\mathrm{g} = 1 0 \mathrm{m} / \mathrm{s} ^ {2})
$
A.
$40.0 \mathrm{~N}$
B.
30.0 N
C.
$18.0 \mathrm{~N}$
D.
44.8 N
Q469
Allen
FRICTION
MCQ
A body of weight 50 N is placed on a horizontal surface. A force of 28.2 N is applied on it as shown in diagram. The frictional force and normal reaction on the body are
A.
2N, 3N
B.
5N, 6N
C.
10N, 15N
D.
20N, 30N
Q470
Allen
FRICTION
MCQ
The coefficient of static friction, $\mu_{s}$ , between block A of mass 4 kg and the table as shown in the figure is 0.3. 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.
A.
$12\mathrm{kg}$
B.
$0.2\mathrm{kg}$
C.
$0.12\mathrm{kg}$
D.
$1.2\mathrm{kg}$
Q471
Allen
FRICTION
MCQ
A rope lies on a table such that a part of it hangs down the table. When the length of hanging part is 1/5 of entire length the rope just begins to slide. The coefficient of friction between the rope and the table is:
A.
1/4
B.
1/6
C.
1/5
D.
3/4
Q472
Allen
FRICTION
MCQ
A block of mass m = 2 kg is placed at rest with respect to moving plank accelerating with acceleration a = 1 m/sĀ². If coefficient of friction between plank and block is Ī¼ = 0.2. The frictional force acting on the block is:
A.
2 N
B.
4 N
C.
3 N
D.
none of these
Q473
Allen
FRICTION
MCQ
In the given figure a monkey of climbing up a rope hanging from the roof with acceleration a. The coefficient of static friction between the body of the monkey and the rope is $\mu$ . value of friction force on the monkey is:-
A.
mg
B.
m(g + a)
C.
$\mu$ mg
D.
m(g - a)
Q474
Allen
FRICTION
MCQ
A block has been placed on an inclined plane with the slope angle $\theta$ , the block slides down the plane at constant speed. The coefficient of kinetic friction is equal to:
A.
$\sin \theta$
B.
$\cos \theta$
C.
g
D.
$\tan \theta$
Q475
Allen
FRICTION
MCQ
A car is moving along a straight horizontal road with a speed $2v_{0}$ . If the coefficient of friction between tyres and the road is $\mu$ . The shortest distance in which the car can be stopped is:
A.
$\frac{v_{0}^{2}}{2\mu g}$
B.
$\frac{v_{0}^{2}}{\mu g}$
C.
$\left(\frac{v_{0}}{\mu g}\right)^{2}$
D.
$\frac{2v_{0}^{2}}{\mu g}$