An asteroid has a mass of 3.66 x 10^20 kg and a radius of 8.2 x 10^5 m. If a 25 kg mass is dropped fro 10 m above the "ground" of the asteroid, how long will it take the mass to fall to the ground?
a=GM/r^2 solve for a.
then
10=1/2 a t^2 solve for time t.