A worker pushes a box in a factory. In each case, decide which force has the greater magnitude: the force exerted by the worker on the box or the force exerted by the box on the worker.

(a) The box is heavy and does not move no matter how hard the worker pushes.

(b) Some contents are removed, and now when pushed the box slides across the floor at constant speed.

(c) The worker pushes harder, and the box accelerates.