1. The problem statement, all variables and given/known data There's a sphere with the mass of the earth and same radius.It rotates at constant speed. It hhas the period of the earth. a mass of a kg sits on the surface. 1) find grav force on mass 2) find centripetal force on mass 3) find the difference in magnitude between them 4) suggest a value of acceleration of free fall for the mass. 2. Relevant equations 3. The attempt at a solution Cant do last part; the way I see it is that the centripetal force does not exist separately; it is criteria for circular motion at constant speed. So clearly the gravitational force over-provides, but I dont understand how this excess is related to the acceleration.