# Math Help - help with physics

1. ## help with physics

A 650 kg satellite orbits at a distance from the Earth's center of about 7.2 Earth radii. What gravitational force does the Earth exert on the satellite?

how would I set this up and what equation would I use

2. ## Re: help with physics

Use Newton's law of gravity:

$F=G\frac{m_1m_2}{r^2}$

or find the weight of the satellite at the surface of the Earth, then use the fact that the force due to gravity varies inversely as the square of the distance from the center of the Earth. This method is easiest, as you don't need to use Newton's gravitation constant, or know the mass and radius of the Earth.

3. ## Re: help with physics

What? How do you write that?

4. ## Re: help with physics

Originally Posted by Louisana1
What? How do you write that?
$\frac{650 \cdot 9.8}{7.2^2}$