- #1
Freemark
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Homework Statement
Gerald stands on the roof looking up at the full moon, which has a mass of 7.39 x 10^22 kg. At this moment, Gerald is 3.77 x 10^8 m from the center of the moon. If the mass of the Earth is 5.96 x 10^24 kg, and the radius of the Earth is 6.39 x 10^6 m, what is the ratio of (Gerald's attraction to the moon) to (Gerald's attraction to the earth)?
Homework Equations
F=G[itex]\frac{M1*M2}{r^2}[/itex]
The Attempt at a Solution
So the first thing I know I need to solve for is the radius of the moon. I wasn't sure how to go about this so I decided that R[itex]_{Gerald from moon}[/itex] - R[itex]_{Earth}[/itex] = R[itex]_{Moon}[/itex] I feel like that's wrong, but I got an answer of 3.71x10[itex]^{8}[/itex].
Next I tried to use the gravity formula (posted above) to find the "F" values for the moon and the earth. I got:
F[itex]_{moon}[/itex] = 7.927x10[itex]^{28}[/itex] and
F[itex]_{earth}[/itex] = 4.597x10[itex]^{30}[/itex]
Then I just divided the moon value by the Earth value to get a ratio. The answer wasn't correct, and I feel like it has to do with the first part. Problem is, I have no idea where to go. Some help would be appreciated.