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Manipal MET2016PhysicsCenter of Mass, Momentum and Collision

Four identical balls, A, B, C and D are placed on a smooth horizontal plane such that B, C and D are in one line and are in contact and A is kept along the same line but a distance away. Now, A is set in motion with speed v along the line and it strikes the ball B . After this collision, which is elastic.

Options

  1. ABalls A, B, C will be at rest and D will move with speed v
  2. BA will be at rest, where B, C and D will move together with speed v / 3
  3. CA will rebound with speed v / 2 while B, C and D will move together with speed v / 2
  4. DA, B, C and D will move together with speed v / 4

Correct answer

A. Balls A, B, C will be at rest and D will move with speed v

Step-by-step solution

It is a case of elastic collision, whole of energy of A is transferred to D .

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