physics
posted by kelly .
Planet Z is 1.00×10^4 km in diameter. The freefall acceleration on Planet Z is 10.0 m/s^2.
a)What is the mass of Planet Z?
b)What is the freefall acceleration 9000 km above Planet Z's north pole?

"g"=GM/radius^2 solve for M
Then, the second: "g"=GM/(radius+9000km)^2 
1.28*(10)^18