Applied forward force = 200 N 2. Backward kinetic frictional force (limiting frictional force exerted by the floor on the wooden box) Since the net force is zero; hence kinetic frictional force = 200 N. Therefore, in this situation, the backward frictional force (limiting frictional force) acting on the box is 200 N, equal to the applied force but in the opposite direction. 16. A pair of Oxen exerts a force of 140 Newtons while ploughing the field. The field ploughed is 15 metres long. The work done in ploughing the length of the field is: