A single – plate clutch has a friction disc with inner and outer radii of 20 mm and 40 mm, respectively. The friction lining in the disc is made in such a way that the coefficient of friction mvaries radially as m=0.01 r, where r is in mm. The clutch needs to transmit a friction torque of 18.85 kN.mm. As per uniform pressure theory, the pressure (in MPa) on the disc is ________