Answer: Second law.
- A First law
- B Second law
- C Third law
- D Law of gravity
Correct answer: B. Second law
Explanation: Newton's second law: Net force = mass x acceleration, i.e., F = ma.
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.