Satellite orbits
The farther from Earth, the slower a satellite orbits.
Gravity provides the centripetal force for the satellite's circular motion, which gives v = √(GM/r) and T = 2π√(r³/GM): the higher the orbit, the lower the orbital speed and the longer the period, independent of the satellite's own mass. Just above the surface the speed is about 7.9 km/s, the first cosmic velocity; a geostationary satellite orbits at about 6.6 Earth radii.
Period vs. orbital radius
T² is proportional to r³ (Kepler's third law); a geostationary satellite sits at about 6.6 R with a period of 24 h.
Think about it
If the satellite's mass is doubled, does its orbital period change?
No. The satellite's mass does not appear in T = 2π√(r³/GM); mass only affects the size of the gravitational force. Adjust "Satellite mass" and see that the period and speed stay the same.
Model assumptionsCircular orbit · Earth treated as a uniform sphere · Air drag neglected
Data log
Set the parameters and click “Record data”. Record several rows with different parameters to plot their relationship and fit a straight line; pause and record at different times to study how a reading changes with time.