Physicshard · Past Paper

What is the work done by friction on a body of mass m sliding down an inclined plane of length L and inclination angle theta?

AmgL sin(theta)
Bu mgL cos(theta)
C- u mgL cos(theta)
DZero

✓ Correct Answer: C- u mgL cos(theta)

Friction force f = uN = u mg cos(theta). Work = -fL = -u mgL cos(theta). The negative sign indicates it opposes motion.

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