Question

1. A ball A is thrown up vertically with speed u. At the same instant, another ball B, at rest, is released
from a height h. At time t, the speed of A relative to B is
(a) u (b) u-2gt
(c) u2 − 2gh (d) u-gt
2. A cricket ball of mass 150 g moving with a velocity of 12 m/s is hit by a bat so that it turns back with a
velocity of 20 m/s. The force of the blow acts for 0.01 second. The average force exerted by the bat on
the ball is
(a) 120 N (b) 240 N
(c) 480 N (d) 960 N
3. For a given motion, the relationship between time t and distance x is found out to be t = αx2 + βx, where
α and β are constants. Considering v as velocity, the retardation will be given by,
(a) 2αv3 (b) 2βv3
(c) 2αβv3 (d) 2β2v3
4. The shaft of a motor rotates at a constant angular velocity of 3000 rpm. The radians, it has turned in
1second, is
(a) 1000 π (b) 100 π
(c) π (d) 10 π
5. If suddenly the gravitational force of attraction between the Earth and a satellite revolving around it
becomes zero, then the satellite will
(a) Continue to move in its orbit with the same velocity
(b) Move tangentially to the original orbit with the same velocity
(c) Become stationary in its orbit
(d) Move towards the Earth
6. A body floats with 1/3 of its volume outside water. The same body floats with 3/4 of its volume inside
another liquid. The density of the other liquid is
(a) 9/4 gm/cc (b) 4/9 gm/cc
(c) 8/9 gm/cc (d) 2/9 gm/cc
7. A metal wire of length L, cross sectional area A and Young’s modulus of elasticity Y, behaves like a
spring. The spring constant k is given by
(a) k =YA/L (b) k = 2YA/L
(c) k= YA/2L (d) k= YL/A
2
8. Liquid rises in a capillary to a height h. In which of the following case will the liquid rise more than h?
(a) In an elevator accelerated downwards
(b) In an elevator accelerated upwards
(c) On the poles
(d) None of the above
9. What is the phase difference between the two waves represented by y1=A sin (ωt+kx) and y2=A cos
(ωt+kx)?
(a) 0 (b)
2
π
(c) π (d)
4
π
10. A coin is placed on a horizontal platform that undergoes vertical simple harmonic motion of angular
frequency ω. The amplitude of oscillation is gradually increased. The coin will leave contact with the
platform for the first time
(a) At the mean position of the platform (b) At an amplitude of g/ω2
(c) At an amplitude of g2/ω2 (d) At the highest position of the platform

Answer 1

- A cricket ball of mass 150 g moving with a velocity of 12 m/s is hit by a bat so that it turns back with a
velocity of 20 m/s. The force of the blow acts for 0.01 second. The average force exerted by the bat on
the ball is
(a) 120 N (b) 240 N
(c) 480 N (d) 960 N
3. For a given motion, the relationship between time t and distance x is found out to be t = αx2 + βx, where
α and β are constants. Considering v as velocity, the retardation will be given by,
(a) 2αv3 (b) 2βv3
(c) 2αβv3 (d) 2β2v3
4. The shaft of a motor rotates at a constant angular velocity of 3000 rpm. The radians, it has turned in
1second, is
(a) 1000 π (b) 100 π
(c) π (d) 10 π
5. If suddenly the gravitational force of attraction between the Earth and a satellite revolving around it
becomes zero, then the satellite will
(a) Continue to move in its orbit with the same velocity
(b) Move tangentially to the original orbit with the same velocity
(c) Become stationary in its orbit
(d) Move towards the Earth
6. A body floats with 1/3 of its volume outside water.