Question

Six identical balls are lined in a straight groove made on a horizontal frictionless surface as shown in fig. Two similar balls each moving with a velocity v collide with the row of six balls from left. What will happen-

Answer 1

It depends upon the phenomenon "Conservation of Momentum".

Step-by-step explanation:

• All six balls are having the same mass say 'm'.  

• On colliding with another ball, their velocity will get exchanged.  

• When a ball with velocity v moves and colloids to another ball( at rest) than the first ball become stationary and the second ball starts moving with velocity v.
• Thus last two balls 3 and 4 will move with the same velocity 'v' and previous two balls 1 and 2 will come to rest position.

Answer 2

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The two particles having equal mass exchange their respective velocities after a head-on perfectly elastic collision. Thus when the two similar balls moving with speed collide  elastically with the row on extreme left end, then the two balls from the extreme right end move with the speed each while the other remaining balls remain at rest.