Calculating Satellite Speed Based on Orbit Period

[phobia]

Homework Statement

A satellite is in a circular orbit about the Earth (M = 5.98 x 1024 kg). The period of the satellite is 7.12 x 104 s. What is the speed at which the satellite travels?

2. The attempt at a solution
I used the equation:

http://img171.imageshack.us/img171/7176/math062gg0.gif

Re-arranged it to isolate r:

http://img74.imageshack.us/img74/9274/math065rr5.gif

After I got radii, i solved for velocity:

http://img171.imageshack.us/img171/3975/math053pd6.gif

My answer: 1.26x10^7 m/s
Teacher: Incorrect

Note: The numbers in the equations are not the actual ones i used.

 

[learningphysics]

The equations seem right to me. Seems like something went wrong when plugging in the numbers. What are the actual numbers you used?

 

[m2003]

Your method for calculating the satellite speed is correct. However, your answer may be incorrect due to rounding errors or incorrect values used in the equations. I would recommend double-checking your calculations and using the actual values given in the homework statement to get a more accurate answer. Additionally, it would be helpful to show your work in more detail so that your teacher can identify any mistakes and provide feedback on how to improve your method. Keep up the good work in using mathematical equations to solve scientific problems!