# Surface Gravity on Mars

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The surface gravity on a planet can be determined from
Newton
's Law of Universal Gravitation:

This says that a planet of mass m_{1}

and radius R

will exert a force on an object (you) of mass m_{2}

So we can relate the force on the surface of Mars to the
force on the surface of the Earth.

It will change like:
Since Mars has a mass that is 0.11 times the mass of the Earth

and a radius that is 0.53 times the radius of the Earth

we expect the surface gravity to be
- 0.11/(0.53)
^{2} = 0.4 times the Earth's