Problem 4-27

4-27.  The front wheels of an experimental rear-drive vehicle have a radius of 300 mm and are designed with disk-type brakes consisting of a ring A with outside and inside radii of 150 mm and 75 mm, respectively. The ring, which does not turn with the wheel, is forced against the wheel disk with a force P. If the pressure between the ring and the wheel disk is uniform over the mating surfaces, compute the friction force F between each front tire and the horizontal road for an axial force P = 1 kN when the vehicle is powered at constant speed with the wheels turning. The coefficient of friction between the disk and ring is 0.35.