1. The bob of a simple pendulum (mass m and length l) dropped from a horizontal position strikes a block of the same mass elastically placed on a
horizontal frictionless table. The K.E. of the block will be
a) 2 mgl
b) mgl/2
c) mgl
d) 0
Explanation:
2. From a stationary tank of mass 125000 pound a small shell of mass 25 pound is fired with a muzzle velocity of 1000 ft/sec. The tank recoils
with a velocity of
a) 0.1 ft/sec
b) 0.2 ft/sec
c) 0.4 ft/sec
d) 0.8 ft/sec
Explanation: According to conservation of momentum
Momentum of tank = Momentum of shell
125000 × vtank = 25 × 1000
vtank = 0.2 ft/sec
3. A bomb of 12 kg explodes into two pieces of masses 4 kg and 8 kg. The velocity of 8kg mass is 6 m/sec. The kinetic energy of the other mass is
a) 48 J
b) 32 J
c) 24 J
d) 288 J
Explanation:
4. A rifle bullet loses \[1\diagup20^{th}\] of its velocity in passing through a plank. The least number of such planks required just to stop the bullet is
a) 5
b) 10
c) 11
d) 20
Explanation: Let the thickness of one plank is s
if bullet enters with velocity u then it leaves with velocity
5. A body of mass 2 kg is thrown up vertically with K.E. of 490 joules. If the acceleration due to gravity is 9.8 \[m\diagup s^{2}\] , then the height at which the
K.E. of the body becomes half its original value is given by
a) 50 m
b) 12.5 m
c) 25 m
d) 10 m
Explanation:
6. Two masses of 1 gm and 4 gm are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is
a) 4 : 1
b) \[\sqrt{2}:1\]
c) 1 : 2
d) 1 : 16
Explanation:
7. If the K.E. of a body is increased by 300%, its momentum will increase by
a) 100%
b) 150%
c) \[\sqrt{300}%\]
d) 175%
Explanation:
8. A light and a heavy body have equal kinetic energy. Which one has a greater momentum ?
a) The light body
b) The heavy body
c) Both have equal momentum
d) It is not possible to say anything without additional information
Explanation:
9. If the linear momentum is increased by 50%, the kinetic energy will increase by
a) 50%
b) 100%
c) 125%
d) 25%
Explanation:
10. A free body of mass 8 kg is travelling at 2 meter per second in a straight line. At a certain instant,the body splits into two equal parts due to
internal explosion which releases 16 joules of energy. Neither part leaves the original line of motion finally
a) Both parts continue to move in the same direction as that of the original body
b) One part comes to rest and the other moves in the same direction as that of the original body
c) One part comes to rest and the other moves in the direction opposite to that of the original body
d) One part moves in the same direction and the other in the direction opposite to that of the original body
Explanation:
