# Compute the distance between the Earth and the Moon

## Homework Statement

14.99 Assuming that the orbit of the moon around the earth is a circle (its
eccentricity is actually 0.055), and knowing that the period of the orbit is 27.3
days, compute the distance in kilometres between the centers of the earth and moon.

## The Attempt at a Solution

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Can you check my solution?

#### Attachments

• 22.2 KB Views: 173

PeroK
Homework Helper
Gold Member
2020 Award
Have you ever heard of a thing called "algebra"?

berkeman
Mentor
Have you ever heard of a thing called "algebra"?
Well, 240,000 miles is about 384,000 km, so the answer looks close to right. Are you seeing algebra errors?

PeroK
Homework Helper
Gold Member
2020 Award
Well, 240,000 miles is about 384,000 km, so the answer looks close to right. Are you seeing algebra errors?
The numerical answer looks correct. It just looks like "plug and chug" gone mad to me.

It would have been nice to see a formula for ##r## in terms of ##G,M, T##.

Am I expecting too much?

berkeman
Mentor
Ah, got it. Yeah, I only checked the final answer because I was having some trouble following his equations and work. Nice job converting units, though...

PeroK