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Physics · WORK, ENERGY AND POWER
हिन्दीA raindrop of mass \( 1.50\text{ g} \) falls from a height of \( 1.20\text{ km} \) under the action of gravity and an opposing air resistance. If it hits the ground with a terminal speed of \( 40.0\text{ m s}^{-1} \) (taking \( g = 10\text{ m s}^{-2} \)), the work done by the resistive force is:
Correct answer · Option 1
\( -16.8\text{ J} \)
Explanation
\( \Delta K = \frac{1}{2}mv^2 = \frac{1}{2}(1.5\times 10^{-3})(1600) = 1.2\text{ J} \). Work done by gravity \( W_g = mgh = (1.5\times 10^{-3})(10)(1200) = 18.0\text{ J} \). Resistive work \( W_r = \Delta K - W_g = 1.2 - 18.0 = -16.8\text{ J} \).
