Q. Which of the following situations exemplify the concept of work being done in physics?

1. A person pushing a stationary wall for an hour.
2. A coolie walking on a horizontal platform with load on his head.
3. A ball thrown vertically upwards against gravity.
4. A falling apple hitting the ground.

Select the correct option using the codes given below:
Answer: Only 3 and 4
Notes: Work in physics is force multiplied by displacement in the direction of force. In option 1, no displacement occurs, so no work is done. In option 2, the force applied is vertical while displacement is horizontal, hence no work in physics context. In options 3 and 4, there is displacement in the direction of force, so work is done.