When a stiff rectangular card is dropped in still air with its long axis horizontal, it often settles into a regular mode of motion; while revolving around its long axis it descends along a path that is inclined to the vertical at a nearly constant angle. We show experimentally that the tumbling frequency of a card of length width w and thickness d scales as consistent with a simple dimensional argument that balances the drag against gravity.
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Letter| January 01 1999
William S. Ryu;
L. Mahadevan, William S. Ryu, Aravinthan D. T. Samuel; Tumbling cards. Physics of Fluids 1 January 1999; 11 (1): 1–3. https://doi.org/10.1063/1.869919
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