Halley's comet moves about the Sun in a highly elliptical orbit. At its closest approach, it is a distance of 8.90 1010 m from the Sun and has a speed of 54 km/s. When it is farthest from the Sun, the two are separated by 5.30 1012 m. Find the comet's speed at that point in its orbit.

Answer 1

Nevermind figured it out, just have to use m1v1=m2v2.

Answer 2

v² =G•M/R²
(v1/v2)²=R2/R1,
v2=v1•sqrt(R1/R2)