Using Kepler's Third Law to find mass

  • #1
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Homework Statement


The fictional planet Snazbort has a fictional moon Pingdol. Pingdol has an orbital period of 7.68 days and a semimajor axis of 92.53×109. Use Kepler's Third Law to estimate the mass of Snazbort.

Homework Equations


T^2=4pi^2*a^3/(GM)

where 2a is the length of major axis
T is the time required for it to travel once around its elliptical orbit
G is gravitational constant
M is mass

The Attempt at a Solution


I've tried plugging in the numbers and I can't seem to figure out how I'm supposed to enter them. I'm also not entirely sure how I even get G. The G I used is from another question.

If it helps at all, the screenshot is here along with my "best" attempt.
http://i.imgur.com/jVZP7u8.png

EDIT: I got the answer. I was supposed to change T into seconds -_-
 

Answers and Replies

  • #2
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Pingdol has an orbital period of 7.68 days and a semimajor axis of 92.53×109
Is that semimajor axis supposed to be 92.53 X 109? What are the units?

It's important to keep track of the units, which maybe you've already found out with the days vs. seconds units in T.
 

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