1. The problem statement, all variables and given/known data Three satellites orbit a planet of radius R. Satellites s1 and s3 have mass m. Satellite s2 has a mass of 2m. Satellites s1 & s2 have orbits 2R from the center of the planet. Satellite s3 has an orbit of 3R from the center of the planet. Satellite s1 orbits in 250 minutes and the force on s1 is 10,000 N a)What are the periods of s2 and s3? b)What are the forces on s2 and s3 2. Relevant equations T= [(4pi)^2/GM]*r^3 3. The attempt at a solution As I'm starting this problem, I'm wondering: Do I have to consider the forces between the satellites as well? And if I do, how will I know the distances between them? Or is the force on s1 only the force from the gravity of the planet? Can I get some suggestions on how to start this?