StellarIn Unit 2, you learned about uniform circular motion and how gravitational force can act as a centripetal force to keep a satellite or planet in orbit. However, according to Kepler’s First Law, all orbits are actually elliptical, with the central mass (e.g., the Sun or Earth) located at one focus of the ellipse.
In AP Physics C: Mechanics, circular orbits are often used as an approximation because they are easier to model mathematically. Circular orbits assume that:
The radius of the orbit remains constant.
The speed of the satellite remains constant.
The motion of the central body is negligible due to its much greater mass.