Four smooth steel balls of equal mass at rest are free to move along as straight line without friction. The first ball is given a velocity of `0.4 m//s` It colloids 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. `0.4 m//s`
B. `0.2 m//s`
C. `0.1 m//s`
D. `0.05 m//s`

Answer

A