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
m1v1 = m2v2
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 is projected at 60° to the horizontal with a kinetic energy K. The kinetic energy at the highest point is
K
0
K/2
K/2
D.
K/2