Is it possible to find orbital velocity depending on time?

[hmvince]

A satellite is in orbit around earth,
(you know G, mass of earth, etc. but NOT the radius)
is it possible to find orbital period?

 

[Creator]

A satellite is in orbit around earth,
(you know G, mass of earth, etc. but NOT the radius)
is it possible to find orbital period?

If only G and mass are all that is known, then No. According to Kepler's Law you must know the radius to get the orbital period, (or vice versa). All you can determine with only G and M is the ratio of the orbital period squared to the radius cubed...which is equal to 4(pi)^2 / GM.

Creator

 

[hmvince]

Sorry about the late reply, but thankyou very much.
If it's not too much trouble, when calculating the mass of the Earth using the moon as a reference and Kepler's 3rd Law, is it correct to subtract the moon's mass after completing the sum:

m[SUB]e[/SUB] = (4*(pi)[SUP]2[/SUP]*r[SUP]3[/SUP]) / (G*t[SUP]2[/SUP])

m[SUB]e[/SUB] = (4*(pi)[SUP]2[/SUP]*385000000[SUP]3[/SUP]) / (G*2358720[SUP]2[/SUP])

m[SUB]e[/SUB] = 6.07[SUB]E[/SUB]+24

Should I be subtracting the moons mass to get:

m[SUB]e[/SUB] = 6.07[SUB]E[/SUB]+24 - 7.36[SUB]e[/SUB]+22  =   5.99[SUB]E[/SUB]+24

I know its not a big difference but I would like to be doing this correctly.
Thanks very much