A force exerted on an object without doing work on the object is when the force is perpendicular to the displacement of the object. In this case, the work done by the force is zero because the dot product of the force and displacement vectors is zero.

An example of this is when a person pushes a wall. The person exerts a force on the wall, but the wall does not move. In this case, the work done by the person is zero because the displacement of the wall is zero.