1. The problem statement, all variables and given/known data An explorer wants to find the mass and radius of a planet he has landed on. He uses a pendulum he has with him and observes it takes a period of T1 to complete. He then climbs 2km up and observes period t2. Find planetary Radius r and Mass m 2. Relevant equations g = GM/r^2 T = 2pi(sqrt(L/g) 3. The attempt at a solution g= 4pi^2L/T1^2 = Gm/r^2 #1 ----- 4pi^2L/T2^2= Gm/(r^2 + 2000)#2 I took #1 and solved for r, r=sqrt((GMT1^2)/4pi^2L) input that in two and came up with GmT1^2 + L8000pi^2= GmT2^2 after canceling M=8000pi^2L/G(t2^2-T1^2) when i evaluate this I get a reasonable mass, 5.~ *10^15 but my radius is way to small any thoughts?