# Mass and Radius of a Planet given v

1. Oct 5, 2008

### chitoboy18

1. The problem statement, all variables and given/known data
While visiting Planet Physics, you toss a rock straight up at 13m/s and catch it 2.7s later. While you visit the surface, your cruise ship orbits at an altitude equal to the planet's radius every 210min . What is the mass and radius of the planet Physics????

2. Relevant equations

M=v^2r/G M=4pi^2r^3/GT^2

You have two pieces of information, each of which gives you an equation to solve. When you've done that, you can substitute one in the other to get the answers. You also need $s = ut + \frac{1}{2} at^2$ for the first bit, and you need to work out how the orbit period relates to the speed and radius of orbit.