LexBrew
Usage Entry 1328 / 1350 60-second read

Mass vs. Weight

The amount of matter (constant) versus the force gravity exerts (varies with gravity).

The comparisoni

✗ Wrong

My weight on the Moon is the same as on Earth.

✓ Correct

My mass on the Moon is the same as on Earth — about 70 kg. My weight is less because lunar gravity is weaker. Mass is constant; weight depends on gravity.

The ruleii

MASS = matter. WEIGHT = gravity pull.

MASS is the amount of matter in an object — constant everywhere. WEIGHT is the force gravity exerts on that mass — varies with location (Earth, Moon, zero-g). Bathroom scales read weight; physics textbooks care about mass. "Weight loss" is technically a mass loss.

Memory aidiii

Remember it like this

Mass stays. Weight changes.

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