Q 11-05-067JEE MainJEE Main 2024 (4 Apr, Shift 1)Easy
A rubber ball falls from a height $h$ and rebounds up to a height of $h/2$. The percentage loss of total energy of the initial system and the velocity of the ball just before it strikes the ground, respectively, are
Answer: (A) $50\%,\ \sqrt{2gh}$
Energy before: $mgh$; after the rebound: $mg\dfrac{h}{2}$. Loss $= \dfrac{mgh/2}{mgh}\times100 = 50\%$.
Speed just before impact: $v = \sqrt{2gh}$.
Solution by Sreeraj P, M.Sc Physics