Q 11-05-044NEETJEE MainMedium
A body of mass $m$ moving with speed $v$ collides with an identical body at rest and sticks to it. The fraction of the initial kinetic energy lost in the collision is
Answer: (C) $\dfrac{1}{2}$
Common velocity $\dfrac{v}{2}$. Final KE $= \dfrac{1}{2}(2m)\left(\dfrac{v}{2}\right)^2 = \dfrac{1}{4}mv^2$, which is half of the initial $\dfrac{1}{2}mv^2$.
So half the kinetic energy is lost (mostly as heat and deformation).
Solution by Sreeraj P, M.Sc Physics