Four smooth steel balls of equal mass at rest are free to move along a straight line without friction. The first ball is given a velocity of 0.4 m/s . It collides head on with the second elastically, the second one similarly with the third and so on. The velocity of the last ball is

Options

A. 0.4m/s
B. 0.2 m/s
C. 0.1 m/s
D. 0.05 m/s

Answer

A

Explanation

In head on elastic collision velocity get interchanged (if masses of particle are equal). i.e. the last ball will move with the velocity of first ball i.e. 0.4 m//s