Final answer:
When you push against a wall, you exert a force, but since the wall does not move, there is no displacement. Therefore, no work is done.
Step-by-step explanation:
An example of a situation in which a force is exerted for a long time but does no work is when you push against a wall. When you push against a wall, you exert a force, but since the wall does not move, there is no displacement. Work is defined as the product of force and displacement, so if there is no displacement, no work is done. In this case, although the force is exerted for a long time, no work is done.