127. The phenomenon of collision of two elastic bodies takes place because bodies

A. immediately after collision come momentarily to rest

B. tend to compress each other till they are compressed maximum possible

C. attempt to regain its original shape due to their elas ticities

D. all the above.

128. The total time of collision and restitution of two bodies,is called

A. time of collision

B. period of collision

C. period of impact

D. all the above.

129. Newton's law of Collision of elastic bodies states that when two moving bodies collide each other, their velocity of separation

A. is directly proportional to their velocity of approach

B. is inversely proportional to their velocity of approach

C. bears a constant ratio to their velocity of approach

D. is equal to the sum of their velocities of approach.

130. For perfectly elastic bodies, the value of coefficient of restitution is

A.(a ) zero

B.0.5

C.1

D. between 0 and 1.

131. A ball of mass 1 kg moving with a velocity of 2 m/sec collides a stationary ball of mass 2 kg and comes to rest after impact. The velocity of the second ball after impact will be

A. zero

B. 0.5 in/sec

C. 1.0 m/sec

D. 2.0 m/sec.

132. The masses of two balls are in the ratio of 2: 1 and their respective velocities are in the ratio of 1 : 2 but in opposite direction before impact. If the coefficient of restitution is 12, the velocities of separation of the balls will be equal to

A. original velocity in the same direction

B. half the original velocity in the same direction

C. half the original velocity in the opposite direction

D. original velocity in the opposite direction

133. A marble ball is rolled on a smooth floor of a room to hit a wall. If the time taken by the ball in returning to the point of projection is twice the time taken in reaching the wall, the coefficient of restitution between the ball and the wall, is

A.0.25

B.0.5

C.0.75

D. 1.0.

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