## Gravity

## Gravity is the universal force of attraction acting between all matter. Gravity one of the weakest forces we know yet all objects with mass-produce a gravitational field. The greater the mass, the greater the gravitational field strength is.

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## Gravitational field strength is measured in Newton's per kilogram (N/Kg). The gravitational field strength on earth is 9.8 N/Kg which means that every kilogram of mass on earth will experience 9.8 Newtons of force.

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## The gravitational field strength is different on different planets, for example on the moon it is only 1.6 N/Kg so when astronauts went to the moon they experienced 1.6 Newtons of force per kilogram which means they weighed less on the moon than they did on the earth.

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## To calculate the weight of an object you use the equation

## weight = mass x gravity.

## For example a 60 kg person on earth would have a weight of __

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## weight = mass x gravity

## weight = 60 x 9.8

## weight = 588 N