Q. A body is moving with 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
Explanation
(b) Let the initial mass of body $= m$
Initial linear momentum $= mv$ …(i)
When it breaks into equal masses then one of the fragment retrace back with same velocity
$\therefore$ Final linear momentum $= \frac{m}{2}( - v) + \frac{m}{2}(v_{2})$ …(ii)
By the conservation of linear momentum
$\Rightarrow mv = \frac{- mv}{2} + \frac{mv_{2}}{2}$
$\Rightarrow v_{2} = 3v$
$i.e$., other fragment moves with velocity $3v$ in forward direction
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.