Q 11-05-025NEETEAMCET 2012 (Medical)Easy
A $3$ kg sphere makes an inelastic collision with another sphere at rest and they stick after the collision. If the composite mass moves with a speed of $\dfrac{1}{4}$ of the initial speed of the $3$ kg sphere, the mass of the second sphere is
Answer: (B) $9$ kg
Concept. Momentum conservation.
Step 1. Equation. $3u = (3 + m)\dfrac u4 \Rightarrow m = 9$ kg.
Answer. $9$ kg (Option B).
Solution by Sreeraj P, M.Sc Physics