Q 11-04-108JEE MainJEE Main 2023 (31 Jan, Shift 1)Easy
$100$ balls each of mass $m$ moving with speed $v$ simultaneously strike a wall normally and are reflected back with same speed, in time $t$ s. The total force exerted by the balls on the wall is
Answer: (B) $\dfrac{200mv}{t}$
Each ball's momentum changes by $2mv$. Total change $=100\times2mv$ in time $t$:
$$F=\frac{200mv}{t}$$
Solution by Sreeraj P, M.Sc Physics