Answer: 0.4.
- A 0.2
- B 0.3
- C 0.4
- D 0.5
Correct answer: C. 0.4
Explanation: mu = f / (mg) = 40 / (10 x 10) = 40/100 = 0.4.
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.