Satellite Orbit around the earth, speed?

[neoncrazy101]

The question is...
A satellite is in a circular orbit about the Earth (M = 5.98 x 1024 kg). The period of the satellite is 6.72 x 104 s. What is the speed at which the satellite travels?

I know the speed is equal to (2piR)/6.72x10^4s But I can't figure out the radius. I know the Earth's radius is 6.38x10^6 but how can I go about figuring out the radius that the satellite travels?

 

[rock.freak667]

You need to use the fact that the gravitational force of attraction between the Earth and the satellite is equal to the centripetal force experienced by the satellite.

You know T, so you can get ω using ω =2π /T.

 

[neoncrazy101]

alright thanks but one question, I am not familiar with the w looking thing nor the 2n. What are they?

 

[rock.freak667]

alright thanks but one question, I am not familiar with the w looking thing nor the 2n. What are they?

ω = omega = angular velocity

n = constant pi = 3.1415...

 

[Fewmet]

The question is...
A satellite is in a circular orbit about the Earth (M = 5.98 x 1024 kg). The period of the satellite is 6.72 x 104 s. What is the speed at which the satellite travels?

I know the speed is equal to (2piR)/6.72x10^4s But I can't figure out the radius. I know the Earth's radius is 6.38x10^6 but how can I go about figuring out the radius that the satellite travels?

You could apply Kepler's Third Law to get the radius. The square of the period divided by the cube of the orbital radius equals 2pi divided by GM (i.e., the universal gravitational constant times the mass of the body at the center of the orbit).

Just be careful with units.