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1924–2020 United States
Robert Kemp Adair (born August 14, 1924 – September 28, 2020) is an American physicist. He is Sterling Professor Emeritus of physics at Yale University.
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Balls curve as a consequence of asymmetries in the resistance of the air through which they pass.
Note that the ball falls at a rather large angle at the end of its flight; the trajectories are not symmetric.
To hit a baseball with dispatch, one needs both to step into the ball and to rotate.
Control pitchers hit corners with an uncertainty of about 3". One must be a fairly good shot to shoot a pistol with that accuracy.
Much of the subtlety of baseball is derived from the fact that so much of the game is played in the region between definitely smooth flow and definitely turbulent flow, at ball velocities greater than 50 mph and smaller than 120 mph.
Almost all of fluid dynamics follows from a differential equation called the Navier-Stokes equation. But this general equation has not, in practice, led to solutions of real problems of any complexity. In this sense, the curve of a baseball is not understood; the Navier-Stokes equation applied to a base ball has not been solved.
A small, but interesting, portion of baseball can be understood on the basis of physical principles. The flight of balls, the liveliness of balls, the structure of bats, and the character of the collisions of balls and bats are a natural province of physics and physicists.
The maximum Magnus force on a ball spinning at a rate of 1800 rpm is seen to be about one-third of the weight of the ball, so we cannot expect a ball spinning at that rate to curve more than one third of the distance it will fall under gravity.
Every 3 feet of lead is worth about one-tenth of a second, and a rolling start is worth a good half second. Indeed, the difference between the runner having his weight mainly on his front foot and mainly on his back foot (but don't let the pitcher catch you leaning!) must be worth more than one-tenth of a second.
The American ash from which bats are made has an unusually high strength-to-weight ratio. Ash was celebrated in medieval times as the only proper wood from which to construct the lances of knights errant; an ash lance was light enough to carry and wield and strong enough to impale the opposition.