Kinetic and static friction are determined experimentally by applying a horizontal force on an object until it moves and for some time after it starts moving. In one such experiment, a 86 N box is placed on a rough horizontal bench and pushed by a horizontal force. The graph below shows the friction force on the box as a function of the push. In what regions of the graph does static and kinetic friction occur?

• A. Static friction: F = 45 N; Kinetic friction: F > 45 N
• B. Static friction: F = 0 N; Kinetic friction: F = 45 N
• C. Static friction: F = 0 - 45 N; Kinetic friction: F > 45 N
• D. Static friction: F = 0 - 45 N; Kinetic friction: F = 45 N

Answer: (C)