Speed of a mass falling into a star given the mass and radius of the star

[TobiasZed]

Homework Statement

Beginning at rest at an extremely large separation, a ball is released and allowed to fall toward a star of mass 3.90E+30 kg and radius 5.70E+7 m. What is the speed of the ball when it reaches the surface?

Relevant Equations

square root of (2*G*M)/(r)

I tried the square root of ((2)(6.67*10^-11)(3.90E+30))/(5.70E+7)
I got 1.55*10^-5 and that is wrong. Maybe I am using the wrong equation but this is the one of professor gave me and I don't know what I am doing wrong :-(

 

[Hill]

Check your calculation.

 

[Orodruin]

… and use units!