Which term describes the resistance to motion?

Which term describes the resistance to motion?

• A. Inertia
• B. Momentum
• C. Velocity
• D. Displacement

Answer: (A)

Inertia is the resistance to motion. It’s the property of matter that makes an object resist changes to its motion: a stationary object tends to stay put, and a moving object tends to keep moving in the same direction and at the same speed unless a net external force acts on it. Mass is a measure of inertia—the more mass something has, the more it resists starting, stopping, or changing direction. That’s why a heavy object is harder to push than a light one, and why a moving car keeps going until brakes or friction slow it down. Momentum describes how much motion an object has, velocity is the speed with direction, and displacement is about how far and in what direction something has moved; none of those describe resistance to motion itself.

Inertia is the resistance to motion. It’s the property of matter that makes an object resist changes to its motion: a stationary object tends to stay put, and a moving object tends to keep moving in the same direction and at the same speed unless a net external force acts on it. Mass is a measure of inertia—the more mass something has, the more it resists starting, stopping, or changing direction. That’s why a heavy object is harder to push than a light one, and why a moving car keeps going until brakes or friction slow it down. Momentum describes how much motion an object has, velocity is the speed with direction, and displacement is about how far and in what direction something has moved; none of those describe resistance to motion itself.