A raindrop of mass 1 g falls from height 1 km and hits the ground at 50 m/s. Take g=10 m s⁻². Work done by gravity and air resistance respectively is:
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A raindrop of mass 1 g falls from height 1 km and hits the ground at 50 m/s. Take g=10 m s⁻². Work done by gravity and air resistance respectively is:

G1 Physics · Accepted Answer

Step 1 — Principle: The net work on a body equals its change in kinetic energy: Wₙₑₜ = Kf − Ki. Step 2 — Working: Gravity does Wg=mgh=.001×10×1000=10 J. Step 3 — Working: Final KE=½(.001)(50²)=1.25 J. Step 4 — Working: With initial KE=0, Wair=ΔK−Wg=1.25−10=−8.75 J. Correct answer: D — 10 J, −8.75 J.