(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A particular comet has an elliptical orbit. When closest to the Sun (perihelion) it is at a distance of 8.823 x 10^10 m and moves with a speed of 54.6 km/s. The greatest distance between this comet and the Sun (aphelion) is 5.902 x 10^12 m.

Calculate its speed at aphelion.

2. Relevant equations

Initial angular momentum = final angular momentum, since Kepler's law states that equal area is swept out at equal times.

3. The attempt at a solution

Li = Lf

Iw = Iw

(mr^2)w = (mr^2)w

(mr^2)(v/r) = (mr^2)(v/r)

Simplifying it, I get the result:

rv = rv

Plugging in the numbers, I get the following answer:

(8.823e10 m)(54,600 m/s) = (5.902e12)(v)

v = 816.225 m/s

= 0.816225 km/s

That's not the right answer, though, and it bothers me like whoa. It's because my professor sent a mass email out yesterday, explaining how a similar problem on the homework had been wrong. So he posted this question up instead, and it's the exact same problem, only with different numbers. When I did the original problem, I got the right answer following this method. Now, it's wrong, and it's confusing me. Any ideas?

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Elliptical Orbits... Unfortunately.

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