PURPOSE: To demonstrate conservation of vector angular momentum.

DESCRIPTION: Sit on the moving chair (chair not rotating) with the wheel spinning and its axis oriented vertically. Reverse the angular momentum vector of the wheel by inverting the wheel, thus causing the entire chair to rotate in the original direction of the wheel rotation. Returning the wheel to its initial orientation causes the chair to cease its rotation. Because the friction in the bearing of the rotating chair is very low, several cycles of this procedure can be completed before the system loses its energy and stops. Using our powered rotator to spin up the wheel, the effect can be fairly dramatic, as seen in these aerial views of the chair rotating in the clockwise or counterclockwise directions. Note that when the blue side wheel markers are showing the wheel is rotating clockwise, and when the red side wheel markers are showing the wheel is rotating counterclockwise. Strobing between the wheel markers and the video framing makes the wheel appear to be rotating in the wrong directions.

SUGGESTIONS:

REFERENCES: (PIRA 1Q40.10)

EQUIPMENT: Rotating chair and bicycle wheel.

SETUP TIME: None.