Here's why:

* Force: A push or pull that can change an object's motion.

* Distance: The amount of space an object moves.

When you apply a force and cause an object to move over a certain distance, you have done work on that object.

Key point: Work is done only when the force causes a displacement (change in position) of the object. If the object doesn't move, no work is done, even if you apply a force.