Working out the geostationary orbit

[dread]

I have been given that this planet has a diameter of 1600km with a uniform density of 52000 per cubic metre. And if its moon is in a geostationary orbit around the planet and assuming that the sidereal is exactly 24 hours. How far is the geostationary orbit above the surface of the planet. And i need the answer in km.

I'm stuck in getting the mass of the planet as so far i have

radius of the geostationary orbit = cubed root of (GM_pT²_p over 4 pi ²)

so therefore the radius = cubed root of (6.6742 x 10^-11 x (mass of the planet which i do not know how to find out x 86400² all over 4 pi ²)

some help would be much appreciated

thanks

 

[tusenfem]

I guess you would have to calculate the volume of the planet?
I guess you would then do something with the density (for which you lack a unit)?
Somehow, magically, this leads to the mass of the planet?

 

[dread]

thanks well I've posted it there now and yeah sorry it was meant to be 5200kg per cubic metre I've changed it for the new post now

 

[stapel]

Neopets "Lenny Conundrum" contest, Round 271 (closes 23 July)

I have been given that this planet has a diameter of 1600km with a uniform density of 52000 per cubic metre...

The actual text of this week's Neopets "Lenny Conundrum" contest puzzle (Round 271) is as follows:

"Assume the world of Neopia is a spherical planet with a diameter of 1600 km with a uniform density of 5200 kilograms per cubic metre. If the moon of Kreludor is in a geostationary orbit around Neopia, and assuming a Neopian sidereal day is exactly 24 hours, how far is that geostationary orbit above the surface of Neopia?"

To get the prize-winning answer for the latest "Lenny Conundrum" contest, try following the instructions here:

. . . . .[/color]Lenny Conundrum Solutions Blog

Another resource might be http://www.able2know.org/forums/viewtopic.php?t=42093 .

Eliz.

 

[cristo]

This is a homework help forum, designed to help students with their homework/classwork problems, not to answer quiz, or contest problems. Thus, I am closing this thread now.