Question

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.

Explanation:

When there is a net force acting on an object, according to Newton's second - law ($F = ma$), the object will accelerate, indicating motion. In option B, friction creates a net force to slow the book down. In option D, in one case there is a net force to the left and in the other a net force upward, which will cause acceleration and thus motion. In option A, balanced forces mean no acceleration and no change in motion state. Option C is incorrect as a net force can indicate motion.

Answer:

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.