Answer: Mass.
- A Mass
- B Weight
- C Momentum
- D Force
Correct answer: A. Mass
Explanation: Inertia is the resistance to a change in the state of motion, and its measure is the mass of the body. Weight depends on gravity and is not a measure of inertia.
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.