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
$$3u = (3 + m)\frac{u}{4} \;\Rightarrow\; 12 = 3 + m \;\Rightarrow\; m = 9\ \text{kg}$$
Solution by Sreeraj P, M.Sc Physics