The driver of the sports car applies his rear brakes
and causes the tires to slip. If the normal force on each rear
tire is 400 lb and the coefficient of kinetic friction between
the tires and the pavement is μ k = 0.5, determine the
average shear stress developed by the friction force on the
tires. Assume the rubber of the tires is flexible and each tire
is filled with an air pressure of 32 psi.