4. A plate clutch consists of one pair of contacting surfaces. The inner and outer diameter of the friction disk is 100 mm and 200 mm, respectively. The coefficient of friction is 0.2, and the permissible intensity of pressure is 1.5 N/mm². Assuming uniform wear theory, determine: (a) The actuating force in the clutch. (b) The friction torque of the clutch. (c) The minimum pressure and its location.