Consider the four free body diagrams. free-body diagrams are diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation. do any of the free body diagrams indicate motion? if yes, which one(s). explain. a) no. in each case, the forces are balanced. b) yes. in b the book is slowing down because of the friction force opposing motion. c) you cannot tell if there is any motion. you can only determine how much force is acting on the objects. d) yes. in b and d. in both cases, there is a net force. in b, there is a net force to the left; in d there is a net force upward.