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gcse_forces_massweight

# Mass and Weight

• Mass is how much of you there is. It is measured in kg and is a scalar. It does not change from place to place.
• Weight is how hard the force of gravity pulls on you. It is measured in N (it is a force!) and is a vector. It does change from place to place.

## Why do we have weight? • The force of gravity pulls you towards the centre of the Earth.
• On Earth, the gravitational field strength is 10 N/kg.
• This means that for every kg of mass you have, 10 N of force is pulling you towards the centre of the Earth…
• On the Moon the gravitational field strength is only 1.6 N/kg. The same mass has less weight on the moon than it does on Earth.
• In space there is no gravity. You are weightless!

## Factors affecting weight

• You have more mass
• You are in a stronger gravitational field. ## The formula!

• Weight = mass x gravitational field strength
• Mass = weight divided by gravitational field strength
• Gravitational field strength = weight divided by mass 