Q. Two elastic blocks $P$ and $Q$ of equal masses $m$ and connected by a massless spring rest on a smooth horizontal surface, as in figure. A third block $R$ of the same mass $M$ strikes the block $P$. After the collision, $P$ and $Q$ will

A) Always move in same direction
B) Sometimes move in same direction and sometime move in opposite directions
C) Always move in opposite directions
D) Be at rest with respect to each other
Explanation

(b) When block $R$ collides with block $P$, it transfers its momentum to block $P$, due to which it moves towards blocks $Q$. The spring connecting blocks $P$ and $Q$ gets compressed, which will push the block $Q$ outwards. Due to outward motion of the block $Q$, the spring gets stretched, the block $Q$ is pulled back. The spring gets compressed, it pushes the block $P$ towards left and so on

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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