1. The problem statement, all variables and given/known data I want to find the period of the satellite. 2. Relevant equations mg = mv^2/r 3. The attempt at a solution I derive the equation mg = mv^2/r v = sqrt(gr) v = ωr and ω = 2π/T T = 2π/ω = 2πr/v Then, T = 2πr/sqrt(gr) But the answer is 2πr/R * sqrt(r/g). I don't know why? Is there anyone can give an explanation to me why it is not correct.