There are three gears one big one and two little ones. The two smaller ones interact with the big gear. The big gear has a radius of 2.5r, the smallest gear has a radius of r and the middle gear has a radius of 1.8r.
The smallest gear is subjected to an external couple of +52 Nm about its axis. Assume the largest gear rotates freely.
a) What couple must be applied to the middle-sized gear so that the system is in equilibrium?
b) If r = 10cm, what are the reaction forces between the gears?