A shaft running at \(500 \mathrm{rpm}\) carries a pulley \(1 \mathrm{~m}\) diameter and drives another pulley by means of ropes with a speed ratio of 2:1. The drive transmits \(200 \mathrm{~kW}\). Angle of groove is \(40^{\circ}\) and distance between pulley centres is \(2 \mathrm{~m}\). The coefficient of friction between rope and pulley is 0.20 . The mass of rope is \(0.12 \mathrm{~kg} / \mathrm{m}\) and has a safe stress of \(1.75 \mathrm{MPa}\). The initial tension in the rope should not exceed \(800 \mathrm{~N}\). Calculate the number of ropes required and rope diameter.