Kepler's Law to Determine Period of Asteroid

[scrambledeggs]

Homework Statement

A newly discovered asteroid orbits at twice the Earth-Sun distance. Find its period of orbit (in years).

Homework Equations

I know that I'm supposed to use Kepler's third law to determine this.
T² = Kr³
K = 4∏²/GM

and the Earth-Sun distance is of course 1 Au

The Attempt at a Solution

I know that the answer should be √8 or about 2.83 years I just don't know how to get there. So frustrating because I know that this is a simple question.

Could it be that K = 1, and R=2 therefore R³ = 8?

 

[PeroK]

Homework Statement

A newly discovered asteroid orbits at twice the Earth-Sun distance. Find its period of orbit (in years).

Homework Equations

I know that I'm supposed to use Kepler's third law to determine this.
T² = Kr³
K = 4∏²/GM

and the Earth-Sun distance is of course 1 Au

The Attempt at a Solution

I know that the answer should be √8 or about 2.83 years I just don't know how to get there. So frustrating because I know that this is a simple question.

Could it be that K = 1, and R=2 therefore R³ = 8?

Think about the relationship between this asteroid's orbit and the Earth's orbit.