Satellite P orbits lower than satellite Q. Which moves faster along its orbit?
A communications satellite is boosted from a low parking orbit to a much higher working orbit. Three things change at once: the gravitational force on it, its speed, and its period. You can predict all three.
This lesson chains the whole topic: one orbit change, three predictions.
Which formula gives the centripetal force for a mass m circling at speed v and radius r?
Three facts from this topic run the whole prediction.
First: gravitational force follows the inverse-square law, so a larger orbital radius means a weaker force on the satellite.
Second: a higher orbit demands a slower satellite.
Third: a larger orbital radius means a longer period.
Now run the boost: the satellite moves to a higher orbit, so its orbital radius grows.
Force: the distance grew, so the gravitational force on the satellite is weaker. Speed: the orbit is higher, so the satellite moves slower. Period: the path is longer and the speed is lower, so the period is longer.
A weather satellite is raised from a 500 km orbit to a 2,000 km orbit. Predict how the force on it, its speed, and its period change.
Write down the change: the orbital radius grows.
Force: the inverse-square law, so a larger radius means a weaker force on the satellite.
Speed: a higher orbit demands a slower satellite.
Period: a larger radius means a longer period.
The force is weaker, the speed lower, and the period longer.
A lunar orbiter is raised to a higher orbit around the Moon. How does the Moon's pull on it change?
A lunar orbiter is raised to a higher orbit around the Moon. How does its period change?
Check the chain against the real sky: the station's 93-minute lap at 400 km, against the TV satellite's full day at 36,000 km.
A Mars orbiter is moved to a lower orbit. Which set of changes is correct?
After a maneuver, Earth's pull on a satellite is stronger and its period shorter. What did the maneuver do?
A navigation satellite is boosted to a higher orbit. Which quantity increases?