Keplar's 2nd Law: Angular Momentum

[justadream]

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So if angular momentum is constant for elliptical orbits,
does that mean that since

L = mvr

as r decreases, v increases at the "sharper*" parts of the elliptical orbit?

*this is where you have higher v, a, F, p, KE

I'm somewhat confused about how "radius" would be applied to a ellipse.

 

[Cawolf]

Velocity increases as the planet moves closer to the sun. The radius is the distance to the sun from the planet.

 

[justadream]

@Cawolf

So does radius decrease then?

 

[Cawolf]

It can - if it was circular then that radius would be constant (by definition).

The planet may have an elliptical orbit with the sun near one end - it will just travel at varying velocities as it is closer or farther from the sun.

 

[justadream]

@Cawolf

Doesn't Keplar's first law say that orbits are elliptical?

Unless you consider a circle a form of an ellipse? If so, what makes some orbitals non-circular ellipses?

 

[Cawolf]

A circle is a special case of an ellipse - just a conic section.