Universal gravitation + orbits question

[davie08]

Homework Statement

A 450kg satellite is to be placed at an altitude of 2.45 x 10^6m above the Earth surface. Calculate the period the satellite will have when orbiting at that altitude.

Homework Equations

m2g = Gm1m2/R^2 = m2v^2 = m2(4pie)^2 R /T^2 = m2 2pie v/T

Ac=4pie ^2 R / T^2

The Attempt at a Solution

Alt= r- rp
2.45x10^6m= r -6.37x10^6m
8.82x10^6m = r

I don't no what equation to use next

 

[Cyosis]

Gm1m2/r^2 = m2v^2

This is wrong it should be Gm_1m_2/R^2 = m_2v^2/r

m2v^2 = m2(4pie)^2 R /T^2

Is also wrong I am not sure what you did here. You're also making one big equality chain which does not hold.

Start with Gm_1m_2/r^2 = m_2v^2/r. Do you know a formula that relates v to T for a circular orbit?

 

[Stratosphere]

there are several aproches to this problem. If it is a circuler or bit you could use use
v_{orbit}=\sqrt{r_{orbit}g_{orbit}}

If it is not a circuler orbit you could use,

T^{2}=\frac{4\pi^{2}\mu}{Gm_{1}m_{2}}r^{3}