# Universal Gravitation

1. Mar 17, 2005

### IamatWork

A 1500 kg satellite is orbiting planet earth. The period is 86400 seconds and the radius is 42200000 meters. To determine the magnitude of attractive force..... you use equation F=GM(sat)M(Earth)/R2. I know that the mass of earth is 6.0*10(exp)7 kg and the gravitational constant is 6.67*10(exp negative 11) N*m2/kg2. My answer comes out to be 3.37 *10(exp)32, which is not one of my options?

2. Mar 17, 2005

did you account for the radius of the earth in your calculation. The distance you need to use is orbital height above erath + earths radius.

Regards,

The mass of the Earth is not $$6*10^{7}kg$$. It is $$6*10^{24}$$ kg.
and don't use r2, but rather $$r^2$$, but I think you knew that already or you probably would have put 2r instead