1. The problem statement, all variables and given/known data If the time period of a satellite in the orbit of radius r around a planet is T, then the time period of a satellite in the orbit of radius 4r is T'= ? 2. The attempt at a solution To be honest I have no idea how to solve this. First I thought Keplers third law may be the solution but even if it is the solution I have no idea how to apply it to solve this question. Thank you for your time and help.