A car navigates a turn in the road at 60 km/h without sliding. The road is inclined at an angle . What does the coefficient of static friction need to be so that the car can take the turn at 90 km/h without skidding?
R(horiz) , where is normal contact force with road and = radius of bend
When speed = 90 km/h (v = 25 m/sec) and car is on point of sliding:
Eliminate from (2) and (3):
, from (1)
Now solve for and you're done.