Q 11-05-176JEE MainJEE Main 2020 (4 Sep, Shift 2)Easy
A person pushes a box on a rough horizontal platform surface. He applies a force of $200\ \text{N}$ over a distance of $15\ \text{m}$. Thereafter, he gets progressively tired and his applied force reduces linearly with distance to $100\ \text{N}$. The total distance through which the box has been moved is $30\ \text{m}$. What is the work done by the person during the total movement of the box?
Answer: (D) $5250\ \text{J}$
Work = area under the force-distance graph.
First $15$ m: $200\times15 = 3000$ J. Next $15$ m (force falls linearly from $200$ N to $100$ N): $\dfrac{200 + 100}{2}\times15 = 2250$ J.
Total $= 5250$ J.
Solution by Sreeraj P, M.Sc Physics