A car traveling at constant speed v rounds a level curve, which we take to be a circle of radius R, If the car is to avoid sliding outward, the horizontal frictional force F exerted by the road on the tires must at least balance the centrifugal force pulling outward. The force F satisfies F = μmg, where μ is the coefficient of friction, m is the mass of the car, and g is the acceleration of gravity, Thus, μmg ‰¥ mv2/R. Show that vR, the speed beyond which skidding will occur, satisfies

And use this to determine vR for a curve with R = 400 feet and μ = 0.4. Use g = 32 feet per second per second.

ugR V gR VR =