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.
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/s^{2}
22 N
4 N
20 N
20 N
C.
20 N
mgh = Fs
F = 20 N
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.
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
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
m_{1}v_{1} = m_{2}v_{2}
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
KL^{2}/2M
zero
zero
A.
A mass ‘m’ moves with a velocity v and collides inelastically with another identical mass. After collision, the 1^{st} 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= mv_{1} cos = θ
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
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)
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/s^{2}
15 m/s^{2}
5 m/s^{2}
5 m/s^{2}
D.
5 m/s^{2}
a = kx/m =10m /s^{2}