Q. Two bodies having same mass $40\ kg$ are moving in opposite directions, one with a velocity of $10\ m/s$ and the other with $7\ m/s$. If they collide and move as one body, the velocity of the combination is
A) $10\ m/s$
B) $7\ m/s$
C) $3\ m/s$
D) $1.5\ m/s$
Explanation
(d) By the conservation of momentum
$40 \times 10 + (40) \times ( - 7) = 80 \times v$
$\Rightarrow v = 1.5\ m/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.