In a Hartnell governor, the radius of rotation of the balls is 50 mm at the minimum speed of 210 rpm. The length of the ball arm is 120 mm and the length of the sleeve arm is 96 mm. The mass of each ball is 2 kg and the sleeve is 3.5 kg. If the stiffness of the spring is 4.3 N/mm, then the initial compression of the spring?
1
15 mm
2
20 mm
3
12.5 mm
4
7 mm