22/06/2019
https://www.facebook.com/Bogdan.John.Vasiliu/photos/a.360271314337053/360739470956904/
The bacterial flagellum, similar in some aspects to an electric motor, is an example of a complex cellular mechanism. The rotor alone can rotate at speeds of up to 6,000 - 17,000 revolutions per minute (rpm), but with the filament attached, only at 200 - 1,000 rpm. The direction of rotation can be switched almost instantaneously. The diameter of the filament is about 20 nanometers, that is about 140 carbon atoms or 70 water molecules side by side.
The flagellum is powered by protons (H+), and sometimes by sodium ions (Na+). It is very efficient and consumes very little energy.
(Bogdan-John Vasiliu, Dialogue with a Nonbeliever, chapter 5.1.1. Complexity of Cell Machines. The image is "quoted" from Wikipedia.)