Physics · WORK, ENERGY AND POWER

A 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:

1. A
   \( 1750\text{ J} \)
2. B
   \( 750\text{ J} \)
3. C
   \( 1250\text{ J} \)
4. D
   \( -1000\text{ J} \)