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Physics · WORK, ENERGY AND POWER
हिन्दीA woman pushes a trunk on a rough railway platform. She applies a force of \( 100\text{ N} \) over a distance of \( 10\text{ m} \). Thereafter, her applied force decreases linearly with distance to \( 50\text{ N} \) at \( 20\text{ m} \). If a constant opposing frictional force of \( 50\text{ N} \) acts on the trunk throughout, the net work done on the trunk over the entire \( 20\text{ m} \) distance is:
Correct answer · Option 2
\( 750\text{ J} \)
Explanation
Work done by applied force \( W_F = (100 \times 10) + \frac{1}{2}(100 + 50)(10) = 1000 + 750 = 1750\text{ J} \). Work done by friction \( W_f = -50 \times 20 = -1000\text{ J} \). Net work done \( W_{\text{net}} = 1750 - 1000 = 750\text{ J} \).
