What is the main difference between mass and weight?

• A. Mass is the amount of matter (constant); weight is the force of gravity on that mass (depends on location)
• B. Mass changes with gravity; weight remains constant
• C. Mass is energy; weight is velocity
• D. Mass remains constant; weight decreases with gravity

Answer: (A)

Mass measures how much matter an object contains, and it stays the same no matter where you are. Weight, on the other hand, is the force gravity exerts on that mass, so it can change with location because gravity isn’t the same everywhere. The relationship is W = m g, where m is mass and g is the local gravitational acceleration. That means your mass is constant, but your weight depends on how strong gravity is where you are.

This explains why the statement that mass is constant and weight is the gravity-based force on that mass is the best description. It captures the intrinsic, location-invariant nature of mass and the location-dependent nature of weight. Other ideas—like mass changing with gravity, or weight being energy or velocity—don’t fit the actual meanings of mass and weight.