Advanced — Vis-Viva EquationHardQuestion 30774
Question
The vis-viva equation for a satellite at radius r in an ellipse (semi-major axis a) is:
- Av² = GM(2/r − 1/a)Correct
- Bv² = GM/r
- Cv² = 2GM/r − GM/a
- Dv² = GM(1/r − 2/a)
Correct answer
v² = GM(2/r − 1/a)
Explanation
The vis-viva equation: v² = GM(2/r − 1/a). For circular orbit (r = a): v² = GM/r. For escape (a = ∞): v² = 2GM/r. It unifies circular, elliptical, and escape trajectories.