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Q: A boy hold 4 kg school bag for 30 seconds, the work done by him will be in joule.
  • A. 4
  • B. 4
  • C. Zero
  • D. 39.20
Correct Answer: Option C - If the boy holds a school bag of 4 kg for 30 seconds, the force exerted by bag will be mg = 4 x10 = 40 N. The boy holds this force for 30 seconds, the work done is zero because displacement is zero Work done = force x displacement = 40 x 0 Work done (W) = 0
C. If the boy holds a school bag of 4 kg for 30 seconds, the force exerted by bag will be mg = 4 x10 = 40 N. The boy holds this force for 30 seconds, the work done is zero because displacement is zero Work done = force x displacement = 40 x 0 Work done (W) = 0

Explanations:

If the boy holds a school bag of 4 kg for 30 seconds, the force exerted by bag will be mg = 4 x10 = 40 N. The boy holds this force for 30 seconds, the work done is zero because displacement is zero Work done = force x displacement = 40 x 0 Work done (W) = 0