1. The problem statement, all variables and given/known data If the Earth, with a radius of 6400 km, were collapsed into a sphere of the same mass, having a radius of 10 km, what would be its rotational period? 2. Relevant equations L = Iw 3. The attempt at a solution I can solve this if the moment of inertia is given but since it isn't I was wondering if there is a way to solve it without knowing the moment of inertia.