Reasoning Skill Builders 4. An external force causes a 3.50-kg box to move at a constant speed up a ramp. The friction force between the ramp and the box is negligible. The external force is exerted on the box in a direction parallel to the ramp. Stewart et al., College Physics for the AP\" Physics 7 Course, 2e, (9 2019 W. H' Freeman and Company a. Construct a free-body diagram for the forces exerted on the box. b. Treat the box as an object upon which the external force is exerted over a displacement d : 5 111, while velocity remains constant, and apply the work-energy theorem to evaluate the numerical value of the work, W, done by this force. What is the total work done on the box by the net force? c. Treat the box and Earth as a system upon which the external force is exerted and apply the principle of energy conservation to evaluate the numerical value of the work, W