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What is weight?

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Quick answer

Weight is the force of gravity pulling on an object's mass. Because it depends on gravity, weight changes with location — you weigh less on the Moon than on Earth — even though your mass (the matter in you) stays the same.

Key things to understand

  1. Weight is a force: the pull of gravity on an object's mass (weight = mass × gravity).
  2. It's measured in newtons (N) scientifically, though everyday scales show it as kilograms.
  3. Weight changes with gravity — less on the Moon, more on Jupiter — while mass stays constant.
  4. A spring scale measures weight; a balance measures mass.
  5. In free fall or orbit, objects feel 'weightless' even though their mass is unchanged.

People also ask

What's the difference between weight and mass?
Mass is the amount of matter in an object and never changes; weight is the gravitational force on that mass and changes with location. Same mass on the Moon, but one-sixth the weight.
Why do you weigh less on the Moon?
Because the Moon's gravity is about one-sixth of Earth's. Weight depends on gravity, so weaker gravity means less weight — though your mass is identical.
Is weight measured in kilograms?
Everyday scales show kilograms, but scientifically weight is a force measured in newtons. Kilograms actually measure mass; the scale converts using Earth's gravity.