Final answer:
In option A, the book does not move, so the force diagram would show the normal force and the force of friction. In option B, the book moves at a constant speed, so the force diagram would show the normal force and the force of friction in the same direction as the applied force. Option C involves a cart moving at constant velocity, which would have a force diagram showing the forward push and the force of friction. Options D and E involve cars on level roads, with D having a balanced force diagram and E having unbalanced forces causing acceleration. Option F involves a parked car with a balanced force diagram.
Step-by-step explanation:
The force diagram that best represents the scenario described in option A, where Mark's physics book is on the desk and Mark pushes horizontally on the book but it does not move, would be a free-body diagram showing only the normal force and the force of friction acting on the book. Since the book does not move, the forces are balanced, with the force of friction equal in magnitude and opposite in direction to the horizontal force applied by Mark.
In option B, where Kendall's physics book is on the desk and Kendall pushes horizontally on the book and it moves across the desk at a constant speed, the force diagram would also include the normal force and the force of friction, but the force of friction would be in the same direction as Kendall's applied force, since the book is moving. The forces are balanced and the net force is zero.
In option C, where Jenny pushes a cart at constant velocity down the grocery store aisle, the force diagram would include a force in the forward direction representing Jenny's push, as well as the force of friction opposing the motion. The forces are balanced and the net force is zero.
In option D, where Eddy is driving his Camaro down a straight, level road while on cruise control, there would be a force diagram showing the force of the engine pushing the car forward, the force of friction opposing the motion, and the normal force. The forces are balanced and the net force is zero.
In option E, where Ryan is accelerating his Dakota down a straight, level road, the force diagram would include the force of the engine pushing the car forward, the force of friction opposing the motion, and the normal force. The net force is non-zero, as the forces are unbalanced and causing the acceleration.
In option F, where Jackie's Viper is parked on the shoulder of the road while she changes a flat tire, there would be a force diagram showing only the force of gravity acting on the car, the normal force from the ground, and the force of friction from the ground. The forces are balanced and the net force is zero.