H1 Physics 8867 · objective lesson
Circular and geostationary orbits
Gravity supplies the centripetal resultant; geostationary motion also requires the correct period, direction and equatorial plane.
Repair the common break
Common misconception: A satellite needs a forward thrust to maintain a circular orbit.
Correct model: Gravity supplies the centripetal resultant; geostationary motion also requires the correct period, direction and equatorial plane.
Worked transfer
In a circular orbit, gravity is the inward resultant and continuously changes velocity direction. A geostationary satellite additionally needs a 24-hour period, an equatorial orbit and eastward motion.
Guided practice
Explain why “A satellite needs a forward thrust to maintain a circular orbit.” fails. Then construct one example that correctly applies circular and geostationary orbits.
Independent practice
Explain why a satellite in a 24-hour polar orbit is not geostationary even if its angular speed matches Earth’s rotation.
Return to the recorded repair plan when the explanation and application are secure enough to re-test.