Answer: Rolling friction.
- A Static friction
- B Kinetic friction
- C Rolling friction
- D All are equal
Correct answer: C. Rolling friction
Explanation: Rolling friction is much less than kinetic (sliding) and static friction. That is why wheels are used.
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.