A 3670 lb car going around an unbanked curve at a constant speed of 25 mph begins to slide (ìs=0.55 and ìk=0.45). What is the radius of the curve?

Answer 1

The static coefficient of friction, which you call ìs=0.55, is the one to use.

Equate the centripetal force to the friction force, and solve for R. The mass of the car will cancel out.

0.55 g = V^2/R
Solve for R.

25 mph = 36.67 ft/s
g = 32.2 ft/s^2

Answer 2

thanks a lot