Variation of Obital Angular Momentum With Radius

A satellite in orbit about a massive body (or a charged particle orbiting another) decreases in speed as the radius increases - increasing  
\[r\]
  means decreasing  
\[v\]
 
Does the orbital angular momentum increase or decrease?
The magnitude of the orbital angular momentum of a satellite is a circular orbit is  
\[L=mvr\]

Equating the centripetal and gravitational forces gives  
\[\frac{mv^2}{r} = \frac{GMm}{r^2}\]

Rearranging for  
\[v\]
:  
\[v = \sqrt{\frac{GM}{r}}\]

Hence  
\[L=m \sqrt{\frac{GM}{r}} r = m \sqrt{GMr} \]

Increasing  
\[r\]
  means increasing  
\[L\]
.

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