Q. 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
A) $0.4\ m/s$
B) $0.2\ m/s$
C) $0.1m/s$
D) $0.05\ m/s$
Explanation
(a) 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 $i.e.$ $0.4\ m/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.