​A uniform disc of radius 1.2 m and mass 0.6 kg is rotating at 25 rad/s around an  axis that passes through centre  and perpendicular to the disc. Rod makes contact with rotating disc with force 4.5 N at point 0.75 m from axis of rotation. Disc is bought to stop in 5 s. What is coefficient of kinetic friction of two materials in contact?   [0.64]