Q. A body of mass $4\ kg$ moving with velocity $12\ m/s$ collides with another body of mass $6\ kg$ at rest. If two bodies stick together after collision, then the loss of kinetic energy of system is
A) Zero
B) $288\ J$
C) $172.8\ J$
D) $144\ J$
Explanation
(c) Loss in K.E. $= \frac{m_{1}m_{2}}{2\left( m_{1} + m_{2} \right)}\left( u_{1} - u_{2} \right)^{2}$
$= \frac{4 \times 6}{2 \times 10} \times (12 - 0)^{2} = 172.8\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.