Learning Objective: Understand how kinetic, gravitational potential and total energy change with radius for circular orbits.
Orbit Radius
Virial Theorem for Circular Orbits:
E = -K = U/2 | K = GMm/2r | U = -GMm/r | E = -GMm/2r "More negative total energy = more tightly bound orbit"
Energy Magnitude Comparison
Bar height shows magnitude; the signed values beneath each bar show whether the energy is above or below zero.
K
+2.50 GJ
U
-5.00 GJ
E
-2.50 GJ
K = +GMm/2r
U = -GMm/r
E = -GMm/2r
Orbit Visualisation
Key Insights
As you increase r: K decreases, while U and E increase (become less negative). The circular orbit becomes less tightly bound. The zero-energy boundary is developed in Lesson 16.