How do I Calculate GMm with Given a and T for Gravitation Problem?

[Clara Chung]

Homework Statement

The question is attached

Homework Equations

Kepler's laws and gravitational equations

The Attempt at a Solution

the question gave me a and T, I related it with Kepler's third law a^3/T^2, then I don't know what to do next. The answer of part a is 1.27 x10^17 /r^2 , part b = 1.9 x 10^27, How can I find GMm as the question only provided a and T?

 

[BvU]

What did you get out of Keplers third law ?

 

[Clara Chung]

What did you get out of Keplers third law ?

If I assume a=r, I can get GM?

 

[BvU]

I think you can ignore the excentricity, yes.

 

[Clara Chung]

I think you can ignore the excentricity, yes.

How can I get m after that?

 

[BvU]

Kepler's third law says a^3/T^2 is 'constant', namely ...
(They only ask for M of Jupiter and that's >> m of moons)

 

[Clara Chung]

Kepler's third law says a^3/T^2 is 'constant', namely ...
(They only ask for M of Jupiter and that's >> m of moons)

Thanks I got part A and B