The Porter governor in the figure has all four arms 300 mm long, pivoted on the spindle axis. Each ball has a mass of 4 kg and the central sleeve has a mass of 24 kg. The radius of rotation of the balls is 180 mm at the lowest position and 240 mm at the highest position, as given in the figure. Neglecting friction, determine (a) the equilibrium speed at the lowest position (answer in rpm), (b) the equilibrium speed at the highest position (answer in rpm) and (c) the lift of the sleeve between these positions (answer in mm). Take g = 9.81 m/s².