Find the period of two identical stars which are in a binary system in circular orbit. This problem is simplified when compared to a real situation in astrodynamics, however it is a great step in beginning to understand how ALL systems orbit their mutual center of gravity, not just one object orbiting another.
*Note* In the final result, the 'pi' term should be squared. In my haste I left that out at the end.
This problem often comes up in high school physics as well as AP Physics 1 and AP Physics C Mechanics.
