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Weight

Weight is the gravitational force on a body. It is the mass times the acceleration of gravity, and it points towards the centre of the Earth. The mass is the same everywhere, but the weight is a little smaller on a high mountain and much smaller on the Moon, because the acceleration of gravity there is smaller. In problems near the Earth's surface we use 9.81 meters per second squared. Do not mix up mass in kilograms and weight in newtons.

G = mg

weight

Symbols

$G$	weight	N
$m$	mass	kg
$g$	acceleration of gravity, 9.81	m/s²

Example

A person has a mass of 70 kg.

$G = 70 \cdot 9.81 = 686.7$ N.

A bathroom scale really reads a force. The number in kilograms is the mass that has that weight.

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Part of Physics 1: Forces and Newton's laws.