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**1. Homework Statement**

Comets travel around the sun in elliptical orbits with large eccentricities. If a comet has speed 2.3×10^4 m/s when at a distance of 2.7×10^11 m from the center of the sun, what is its speed when at a distance of 4.3×10^10 m.

**2. Homework Equations**

I tried using v = ((G*M) / r) ^ 0.5, but I'm not sure if that will work with this problem.

**3. The Attempt at a Solution**

* I tried using conservation of angular momentum (per a tutor's advice), but didn't get the right answer

* I tried using Kepler's 2nd Law (area sweep) because the area that is swept out is the same all around the circle, but again no luck

* I tried using conservation of energy

* I used the equation that I listed above and solved for the mass of the comet by plugging in the 1st velocity and radius. Then I used the mass I came up with, along with the 2nd radius and solved for the velocity (v = 5.8*10^4 m/s). I inputted this answer into my online homework site, and it said that I was close, but not right.

Can someone please help me figure out where I went wrong??

Thanks in advance.