(a) State what is meant by work done by a force. (b) A labourer performs the…
PHYSICS · Subjective · CBSE · Physics · Work and Energy · Work and Energy
Problem
(a) State what is meant by work done by a force.
(b) A labourer performs the following three actions:
(i) lifts a 15kg cement bag vertically upward through 1.2m,
(ii) lowers an identical bag vertically downward through 1.2m,
(iii) carries the bag horizontally across a floor for 8m keeping it at the same height.
For each action, identify whether the work done by the gravitational force on the bag is positive, negative or zero. Give a reason in one or two sentences for every answer.
(c) Explain why the work done by the labourer’s applied force in part (iii) is zero even though he may feel tired after walking the distance.