- 57

- 0

**[SOLVED] need help with keplers 3rd law of periods problem**

**1. Homework Statement**

A 20 kg satellite has a circular orbit with a period of 2.6 h and a radius of 9.4E6 m around a planet of unknown mass. If the magnitude of the gravitational acceleration on the surface of the planet is 8.6 m/s2, what is the radius of the planet?

**2. Homework Equations**

T^2=((4pi^2)/(GM))r^3

a gravity=(GM)/r^2

**3. The Attempt at a Solution**

I used the law of periods to find the mass and then used the second equation to find the radius of the planet but I got a really small number