Question

A body is moving with a velocity $v$ breaks up into two equal parts. One of the part retraces back with velocity $v$. Then the velocity of the other part is

• A. $v$ in forward direction
• B. $3v$ in forward direction
• C. $v$ in backward direction
• D. $3v$ in backward direction

Answer 1

The correct option is B $3v$ in forward direction

Suppose initial mass was $2m$ and the velocity was $v$ then it was the velocity of $center$ of mass.

Given that the first part of mass $m$ started to move with $-v$, $negative$ because $opposite$.

If the second part is moving with $V$ then the velocity of center of mass should be $v$ i.e. $v=\frac{mV+(-mv)}{m+m}$ or $V=3v$

positive so in $forward$ direction.