What is the maximum track angle of inclination you should consider if you wish to minimize energy loss due to slippage of the ball? Support your answer with calculations.

I've included two formulas that i believe may be relevant to answer this question?

http://img176.imageshack.us/img176/7522/formulasef8.png
also, included two pics of the excel sheets i may need.

http://img227.imageshack.us/img227/6070/excel1nr9.png
and

http://img176.imageshack.us/img176/6805/excel2ak2.png
~where theta is the average incline angle.

~theta-c is the angle below which the ball will not slip as it rolls.

~r is the geometric radius of the ball

~r' is the effective rolling radius of the ball on the track.

here are some useful constants:

Useful constants for ball: m= .0097 kg, geom. Radius=.01272 m, rolling radius =.01018 m, moment of inertia = 6.278E-7 kg-m^2

overall, i have alot of information, and i'm not sure which information i need to get the answer.

I'm sure i've added alot of irrelevant info for this problem.

can someone help please.