﻿ A bomb of mass 16 kg at rest explodes into two pieces of masses of 4 kg and 12 kg. The velocity of the 12 kg mass is 4 ms−1 . The kinetic energy of the other mass is | Laws of Motion

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# Laws of Motion

#### Multiple Choice Questions

11.

A mass of M kg is suspended by a weightless string. The horizontal force that is required to displace it until the string makes an angle of 45° with the initial vertical direction is

A.

285 Views

12.

Consider a car moving on a straight road with a speed of 100 m/s. The distance at which car can be stopped is [µ =k 0.5]

• 800 m

• 1000 m

• 600 m

• 600 m

B.

1000 m

317 Views

13.

The block of mass M moving on the frictionless horizontal surface collides with a spring of spring constant K and compresses it by length L. The maximum momentum of the block after collision is

• KL2/2M

• zero

• zero

A.

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# 14.A bomb of mass 16 kg at rest explodes into two pieces of masses of 4 kg and 12 kg. The velocity of the 12 kg mass is 4 ms−1 . The kinetic energy of the other mass is 144 J 96 J 288 J 288 J

C.

288 J

m1v1 = m2v2

506 Views

15.

A particle of mass 0.3 kg is subjected to a force F=−kx with k=15 N/m. What will be its initial acceleration if it is released from a point 20 cm away from the origin?

• 3 m/s2

• 15 m/s2

• 5 m/s2

• 5 m/s2

D.

5 m/s2

a = kx/m =10m /s2

171 Views

16.

A mass ‘m’ moves with a velocity v and collides inelastically with another identical mass. After collision, the 1st mass moves with velocity v/√3 in a direction perpendicular to the initial direction of motion. Find the speed of the 2nd mass after collision

• v

• √3 v

• 2v/√3

• 2v/√3

C.

2v/√3

mv= mv1 cos = θ

738 Views

17.

A player caught a cricket ball of mass 150 g moving at a rate of 20 m/s. If the catching process is completed in 0.1 s, the force of the blow exerted by the ball on the hand of the player is equal to

• 300 N

• 150 N

• 30

• 30

C.

30

(mv-0)
⇒ 0.15 x 20
F = 3/0.1 = 30 N

250 Views

18.

A block of mass ‘m’ is connected to another block of mass ‘M’ by a spring (mass less) of spring constant ‘k’. The blocks are kept on a smooth horizontal plane. Initially the blocks are at rest and the spring is stretched. Then a constant force ‘F’ starts acting on the block of mass ‘M’ to pull it. Find the force on the block of mass ‘m’.

• mF/M

• (M+m)F/m

• mF/(m+ M)

• mF/(m+ M)

C.

mF/(m+ M)

195 Views

19.

Consider a two-particle system with particles having masses m1 and m2. If the first particle is pushed towards the centre of mass through a distance d, by what distance should the second particle be moved, so as to keep the centre of mass at the same position?

• d

• d

A.

457 Views

20.

A ball of mass 0.2 kg is thrown vertically upwards by applying a force by hand. If the hand moves 0.2 m which applying the force and the ball goes upto 2 m height further, find the magnitude of the force. Consider g = 10 m/s2

• 22 N

• 4 N

• 20 N

• 20 N

C.

20 N

mgh = Fs
F = 20 N

395 Views