Satellite and gravitational force

[fa08ti]

a 500 kg satellite experiences a gravitational force of 3000 N, while moving in a circular orbit around the earth.
a: find the radius of the circular orbit
b: find the speed of the satellite
c: find the period of the orbit

attempt

a:
g= GM/r^2
r=sqrt(GM/g)
r= 3.33 x 10^-6 m

am i right?

 

[Clever-Name]

Think about your answer for a second... does 10^-6m make any physical sense?

 

[fa08ti]

not at all...where did i go wrong?

 

[Clever-Name]

Your equation is missing a term for the mass of the satellite:

$$F_{G} = \frac{GMm}{r^{2}}$$

 

[fa08ti]

thanks a lot!