- #1

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http://en.wikipedia.org/wiki/Kepler's_third_law

The planet mass is also added.

So I am not sure what kind of equation I should use to solve sums?

Thanks

- Thread starter dilan
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- #1

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http://en.wikipedia.org/wiki/Kepler's_third_law

The planet mass is also added.

So I am not sure what kind of equation I should use to solve sums?

Thanks

- #2

Doc Al

Mentor

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(a) A circle is special kind of ellipse; I'm sure you instructor approximated the orbits as circular just to keep the calculations easier.

(b) The masses are added in turning Kepler's 3rd law from a statement of proportionality to an equality; it goes beyond Kepler's original law by adding Newton's model of universal gravity.

(b) The masses are added in turning Kepler's 3rd law from a statement of proportionality to an equality; it goes beyond Kepler's original law by adding Newton's model of universal gravity.

I don't know what you mean by "solve sums".

- #3

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Hi

(a) A circle is special kind of ellipse; I'm sure you instructor approximated the orbits as circular just to keep the calculations easier.

(b) The masses are added in turning Kepler's 3rd law from a statement of proportionality to an equality; it goes beyond Kepler's original law by adding Newton's model of universal gravity.

I don't know what you mean by "solve sums".

Thanks alot for replying. We finished orbital motion just 3 days ago and he gave us a work sheet with problems to solve. I think your correct, he approximated the orbits as circular to keep thinngs simple. The equation that I am using is

4pi^2r^3/GM

r- radius of orbit

M - mass of the center object

Thanks

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