How Does Eccentricity Influence Orbital Speed Ratios in Planetary Motion?

AI Thread Summary
The discussion focuses on calculating the ratio of orbital speeds at perihelion and aphelion for a planet with an eccentricity of 0.006800 and a semimajor axis of 0.7233 AU. The user initially attempted to find the ratio using the distances between the foci and angular momentum conservation but arrived at an incorrect result. The correct approach involves using the formulas for aphelion (ra = a(1+e)) and perihelion (rp = a(1-e)) distances. The final ratio of speeds should be calculated as v(p) / v(a) = r(a) / r(p), leading to the correct values for aphelion and perihelion. The user is seeking clarification on their mistake in the calculations.
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Homework Statement


A planet has an eccentricity of 0.006800 and a semimajor axis of 0.7233 AU, find the ratio of ortibal speed at perihelion to that at aphelion.


Homework Equations



d=e x a
L=mvrsin\theta

The Attempt at a Solution


I plugged in and solved for the distance between the foci (0.004918)
and then set the angular momentum constants equal to each other:
m v(p) rmin sin\theta=m v(a) rmax sin\theta
the masses and sin\theta cancel out, so
v(p) x r min = v(a) x r max
and so the ratio is:
v(p) / v(a) = r max / r min

r max is the semimajor axis, and r min is the semimajor axis minus the d as found above:
So, it should be .7233/.718382 which gives me 1.00685, but this was incorrect according to my online homework, could you tell me what I did wrong?
 
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The relation vp/va = ra/rp is correct, but ra and rp are the aphelion and perihelion distances, respectively, and are given by ra = a(1+e) and rp = a(1-e).
 
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