Six identical balls are lined in a straight groove made on a horizontal frictionless surface as shown. Two similar balls each moving with a velocity v collide elastically with the row of 6 balls from left. What will happen

Options

A. One ball from the right rolls out with a speed 2v and the remaining balls will remain at rest
B. Two balls from the right roll out with speed v each and the remaining balls will remain stationary
C. All the six balls in the row will roll out with speed v/6 each and the two colliding balls will come to rest
D. The colliding balls will come to rest and no ball rolls out from right

Answer

B

Explanation

Momentum and kinetic energy is conserved only in this case.