Question

Which of the following is an example of zero work even when the body suffers a displacement from its initial position?

• A. A coolie carrying a load on his head and moving forward on a horizontal road
• B. A fielder catching a ball
• C. A child pushes a wall
• D. A child pulling a toy car

Answer 1

Answer: (A)

A coolie carrying a load on his head and moving forward on a horizontal road

When a coolie carries a load on his head, he applies a force upwards against the weight of the load, i.e., against the gravitational force. And the displacement is forward horizontally. So, the angle between the force and the displacement is ${90}^{\circ }$ and the work done is zero.
To catch a ball, work done is negative as the ball moves in the opposite direction of force before coming to rest.
A child pushing a wall is an example of zero work as the wall suffers zero displacements.
A child pulling a toy car is an example of positive work.