Three identical smooth balls A, B and C lie on a straight line. B and C are initially at rest. A moves toward B with speed 12 m/s. All collisions are perfectly elastic and the balls are identical. If the final speed of C is N m/s, find N.
Physics · Center of maas , Momentum and Collision · collision and types of collision
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Question

Three identical smooth balls A, B and C lie on a straight line. B and C are initially at rest. A moves toward B with speed 12 m/s. All collisions are perfectly elastic and the balls are identical. If the final speed of C is N m/s, find N.

Physics · Center of maas , Momentum and Collision · collision and types of collision

G1 Physics · Accepted Answer

For a one-dimensional perfectly elastic collision between identical masses, the moving ball transfers its velocity completely to the stationary ball. First collision A-B: A comes to rest and B moves with 12 m/s. Second collision B-C: B comes to rest and C moves with 12 m/s. Thus the final speed of C is 12 m/s. Hence N = 12.