In a spring controlled governor of the Hartung type, the lengths of the horizontal and vertical arms of the bell crank levers are 100 mm and 80 mm respectively. The fulcrum of the bell crank lever is at a distance of 120 mm from the axis of the governor. Each revolving mass is 8 kg. The stiffness of the spring is 20 kN/m. If the length of each spring is 120 mm, when the radius of rotation is 70mm and the equilibrium speed is 380 rpm, find the free length of the spring. If the radius of rotation increases to 120 mm, what will be the corresponding percentage increase in speed? Ignore sleeve mass.