An object moves horizontally with initial kinetic energy 10 J and displacement 3î m under force F = (-2î + 3ĵ) N. Its final kinetic energy is:
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An object moves horizontally with initial kinetic energy 10 J and displacement 3î m under force F = (−2î + 3ĵ) N. Its final kinetic energy 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: Only the component along displacement does work: W=F·s=(−2)(3)+3(0)=−6 J. Step 3 — Working: By work–energy theorem Kf=Ki+W=10−6=4 J. Correct answer: C — 4 J.