Archimedes Would Have Approved

Physics prof. Tim Gay

Physicists who are obsessed with American football have puzzled over the mystery of a perfectly thrown pass: [bold added]

The start of a football pass exhibits the properties of “angular momentum”—once launched, it spins away, nose upward, maintaining much of its rotation, but then, after reaching its apex, it falls to earth (and hopefully, into the hands of a wide receiver) nose down, still spinning, still symmetrical.

To [Nebraska professor Tim] Gay, this flight pattern didn’t add up. Physics told him that the ball, at a certain point in its trajectory, should start wobbling and tumbling, counter-clockwise. Gravity alone couldn’t explain why a pass could begin as a beautiful spiral and also finish as a beautiful spiral.

Something else had to be going on.

After years of study they figured it out:

We have shown that the paradox is simply resolved by focusing on the gyroscopic precession driven by the torque that results from the ball’s nonzero angle of attack and by the interaction of that torque with the ball’s angular momentum.

That's all very enlightening---and I'm sure the discovery will help in the development of football-playing robots--but I, as well as 99.99% of the population, prefer to learn how to throw a football from coaches and players.