Re: [Phys-L] LRL vector == another Kepler symmetry + Check Your Work

[Bernard Cleyet <bernardcleyet@redshift.com>]

On 2012, Nov 30, , at 13:19, John Denker wrote:

> Hi --
>
> As everybody knows, the Kepler problem conserves angular momentum and 
> conserves energy.  The same is true of any other problem with a central 
> force that is the gradient of some potential.


Much cut.


I'm too lazy (exaggeration for other irons in the fire) to check this out.  At the recent SOCal AAPT mtng. a presenter claimed the equal area thing is wrong.
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Pari Spolter (Orb Publishing)-Kepler’s second law and conservation of angular momentum

"Kepler’s second law is calculated for 18 planets and asteroids. It is shown that equal areas are swept in equal intervals of time only near the perihelion (P) and the aphelion (A). A highly significant relation between the ratio of the area swept at the average of P and A to the area swept at semimajor (S) in the same interval of time and the eccentricity is presented. The equation is ratio =ab+c with a = −0.617, b = 2, and c = 1.00. The correlation coefficient is 0.9975. The ratio is equal to , which is equal to sin θ, where θ is the smaller angle between the two vectors v and r. Angular momentum is a vector perpendicular to the plane formed by v and r and is conserved, indicating that there is no torque in the direction vertical to the plane of the orbits."

http://www.scaapt.org/meetings/2012mtg1fall/program.htm
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I can't find the paper she gave me (quickly), and this may have nothing to do w/ JD's post -- just a cursory read jogged my memory.

bc may be all wet.  (in addition to behind the ears)