Unit: Dynamics

Each of the following situations represents a different type of work (positive work, no work, and negative work). Match the correct type of work to the correct situation (no explanation necessary).

a) The work done on a book that is falling.

b) The work done by Bob pushing against a brick wall that is not moving.

c) The work done by a curling stone that slides at a constant speed and comes to a stop.

Please help