(adsbygoogle = window.adsbygoogle || []).push({}); 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

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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?

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# Homework Help: Mass of a planet using a pendulum

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