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

TobiasZed
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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 :-(
 
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Check your calculation.
 
… and use units!
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
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