The paradox of the tight spiral pass in American football: A simple resolution
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of Nebraska, Lincoln, NE (United States)
An American football is a rotationally symmetric object, which, when well-thrown, spins rapidly around its symmetry axis. In the absence of aerodynamic effects, the football would be a torque-free gyroscope and the symmetry/spin axis would remain pointing in a fixed direction in space as the football moved on its parabolic path. When a pass is well-thrown through the atmosphere, however, the symmetry axis remains—at least approximately—tangent to the path of motion. The rotation of the symmetry axis must be due to aerodynamic torque; yet, that torque, at first glance, would seem to have precisely the opposite effect. In this work, we explain the action of aerodynamics on the ball's orientation at second glance.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC52-07NA27344
- OSTI ID:
- 1716597
- Report Number(s):
- LLNL-JRNL-809624; 1016047
- Journal Information:
- American Journal of Physics, Journal Name: American Journal of Physics Journal Issue: 9 Vol. 88; ISSN 0002-9505
- Publisher:
- American Association of Physics Teachers (AAPT)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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