Question

In a certain binary star system, each star has the same mass as our sun, and they revolve about their center of mass. The distance between them is the same as the distance between the EArth and sun. Wha tis their period of revolution in years?

Answer 1

You know the force of gravity, you know the radius of rotation.

GMsMs/r^2=Ms v^2/r

but v=2PI r/Period
solve for period.