science
posted by blake .
how much force is required to keep an overgrown 50 kg ferret moving at a constant velocity across a .33 cos of friction floor?

I will assume you mean a "0.33 coefficient of (kinetic) friction floor". Otherwise your question doesn't make sense.
The answer is 0.33 M*g. where M = 50 kg and g = 9.8 m/s^2.
The answer will be the force, in Newtons
I do not think ferrets grow to weigh 50 kg, by the way. 
The most common weight range for adult male ferrets is 2 to 5 lbs. That would be 1 to 2.5 kg, roughly.