We are thinking of a centrifugal regulator. Steam engines had such a regulator once. When the speed starts to increase the steam decreases reacting immediately due to the fast and high increase of the centrifugal (centripetal) force of pendulous masses:
m.
ω
2
FG R−radiusc =R m=g
There is no steam in our case! How should we make such a type of regulator maintain constant speed? It is possible for the DC electrical motor to provide the