Q 11-05-049JEE MainJEE Main 2026 (6 Apr, Shift 1)Easy
The rain drop of mass $1$ g, starts with zero velocity from a height of $1$ km. It hits the ground with a speed of $5\ \text{m/s}$. The work done by the unknown resistive force is ______ J. (Take $g = 10\ \text{m/s}^2$)
Answer: (D) $-9.98$
Work–energy theorem: $W_g + W_r = \Delta K$.
$W_g = mgh = 10^{-3} \times 10 \times 1000 = 10$ J; $\Delta K = \dfrac{1}{2} \times 10^{-3} \times 25 = 0.0125$ J.
$W_r = 0.0125 - 10 = -9.9875$ J $\approx -9.98$ J (closest option).
Solution by Sreeraj P, M.Sc Physics