Answer: 30 N.
- A 0 N
- B 15 N
- C 30 N
- D 60 N
Correct answer: C. 30 N
Explanation: Newton's third law: the wall exerts an equal and opposite force of 30 N on the man.
Free-body diagram of a block on an incline: weight (mg) resolves into mg sinθ along the slope and mg cosθ into the slope, balanced by the normal force N and friction f.
Concept context
Newton's three laws, friction, circular motion, and free body diagrams.