supplemental_video4

Demonstration of a constant torque motor. The axial torque is rapidly compensated by viscous drag between the rotating wooden stick and the air. The system is held at constant elongation z by a thin black sewing thread attached on the lower side in the middle of the wooden stick (not visible in video).
The thread allows the stick to rotate (almost) freely, but at constant z. These are the very conditions studied in the main text.