star orbiting black hole

nicholas123

Hi
I have to describe a method to solve a problem involving a black hole. The only information given is the period of the orbiting star and the radius of the orbit. I have to find the stars mass.

Would i use the equation F=(mv^2)/r and then substitute in v=(2 pi r)/T for the radius where T is the period? Then would i set the original equation equal to G(Mm/r^2) where the first two masses would cancel out and then solve for the final mass?

Thanks

rock.freak667

Equating those two equations, you will only be able to get the mass of the black hole. The star's mass will cancel out.

nicholas123

ok. but the mass i get will be for the star?
thanks

rock.freak667

If the star's mass will cancel out, you will only be left with one mass (and it's not the mass of the star )