Kepler's Second Law: Areal Velocity (dA/dt = L/(2m) = const)

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dA/dt = L/(2m) = const

What each symbol means

SymbolWhat it stands for
AArea swept by radius vector
LAngular momentum magnitude about M
mOrbiting mass

When to use this

Central gravitational force → torque about M is zero → L conserved → areal velocity constant.