Answer: 30 N.
- A 3 N
- B 15 N
- C 30 N
- D 100 N
Correct answer: C. 30 N
Explanation: Kinetic friction fk = mu_k x N = 0.3 x 10 x 10 = 30 N. For constant velocity, applied force = fk = 30 N.
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.