A single disc clutch with both sides of the disc effective is used to transmit 10 kW power at 900 r.m.p. the axial pressure is limited to 0.085 N/mm^2. If the external diameter of the friction lining is 1.25 times the internal diameter find the required dimension of the friction lining and the axial force exerted by the springs. Assume uniform wear conditions. The coefficient of the friction may be taken as 0.3