So, the question could be: Is the Formula for Specific Angular Momentum Correct?

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The discussion centers on the formula for specific angular momentum and its application in calculating eccentricity in orbital mechanics. The formula presented for eccentricity, e = h² / μEarth / (radius at perigee) - 1, raises concerns about the calculation of specific angular momentum, h. It is clarified that h is indeed specific angular momentum, defined as angular momentum per unit mass, calculated as h = (radius at perigee) * (velocity at perigee). The absence of a mass component in the formula is noted, but it is emphasized that specific angular momentum is often used for convenience in orbital calculations. Understanding this distinction is crucial for accurate application of the formulas in orbital mechanics.
Kyle91
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Hey guys

Well I'm doing a group assignment based on orbital mechanics and my partner found a formula for eccentricity which is:

e = h2 / μEarth / (radius at perigee) - 1

Anyway when calculating h he said it was angular momentum:

h = (radius at perigee)*(velocity at perigee)

But it can't be because there's no mass component, so I'm worried we used the eccentricity formula wrong. Is the above formula for h correct? If so, what is it called?

Thanks!
 
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h is specific angular momentum. That is, the angular momentum per unit mass of the orbiting object. Multiply h by mass to find the actual angular momentum.

It's often more convenient to work with specific angular momentum because in almost all cases the various characteristics of an orbit don't depend upon the orbiting body's mass when it's negligible compared to its primary.
 
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