1. The problem statement, all variables and given/known data Consider two uniform spherical planets of equal density but unequal radius. Which of the following quantities is the same for both planets? 2. Relevant equations 3. The attempt at a solution I can't really attempt to solve it because it's not really a "problem." The escape velocity from the planet's surface. The acceleration due to gravity at the planet's surface. The orbital period of a satellite in a circular orbit just above the planet's surface. The orbital period of a satellite in a circular orbit at a given distance from the planet's center. None of the above. I can't find any equations having to do with any of things things that don't rely on either density or radius.