# Robert Adair (physicist)

**Robert Kemp Adair** (born 1924) is an American physicist. He is Sterling Professor Emeritus of physics at Yale University.

## Sourced[edit]

*The Physics Of Baseball* (Second Edition - Revised)[edit]

- 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.
- Chapter 1, Models And Their Limitations, p. 1

- 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.
- Chapter 2, The Flight Of The baseball, p. 7

- 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.
- Chapter 2, The Flight Of The baseball, p. 14

- Note that the ball falls at a rather large angle at the end of its flight; the trajectories are not symmetric.
- Chapter 2, The Flight Of The baseball, p. 15

- 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.**- Chapter 2, The Flight Of The baseball, p. 22

- Control pitchers hit corners with an uncertainty of of about 3". One must be a fairly good shot to shoot a pistol with that accuracy.
- Chapter 3, Pitching, p. 27

- Balls curve as a consequence of asymmetries in the resistance of the air through which they pass.
- Chapter 3, Pitching, p. 28

- 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.
- Chapter 4, Running, Fielding, And Throwing, p. 57

- We not that those players with weaker arms might be better off throwing at a lower angle to get the ball to the plate on the bounce. If the surface is Astroturf, the 90-mph player can gain as much as 0.2 seconds, or 6 feet, on the runner by throwing on the bounce. But if his team is playing on grass and his groundskeeper has kept the grass long and well watered to help his team (which relies on singles, speed, and baserunning), the ball may lose so much speed at the bounce that nothing will be gained.
- Chapter 4, Running, Fielding, And Throwing, p. 61

- To hit a baseball with dispatch, one needs both to step into the ball and to rotate.
- Chapter 5, Batting The Ball, p. 68

- 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.
- Chapter 6, Properties Of Bats, p. 134