Re: When a pitcher throws a ball, when is the ball at its maximum speed?

Date: Mon Dec 4 12:14:39 2000
Posted By: Tom Cull, Staff, Clinical Sciences MR Division, Marconi Medical Systems
Area of science: Physics
ID: 975618659.Ph

Message:

I turn to Robert K. Adair's The Physics of Baseball to answer this question.

The section entitled The hop of the fastball, simply states:

Since the ball slows down considerably on the way from the pitcher to the plate, the "muzzle velocity" of the ball --
as it leaves the pitcher's hand -- is about 8 mph greater than its speed across the plate. The ball loses speed at a rate
of about 1 mph every 7 feet.
(page 30, The Physics of Baseball)

Professor Adair's use of the word "muzzle velocity" is appropriately leading. Bullets shot through the air slow down because moving
through the air creates a drag force that opposes the direction of flight. The drag for a baseball is a function of many things but most importantly, the spin rate of the ball, the air pressure, and the speed of the ball. According to Adair's reprint of measurements, the drag force on a baseball rises from about 0.5 to 1.0 times the weight of the ball over the range 50 to 100 mph.

To see this effect in a silly worst case scenario, try throwing any type of plastic baseball (whiffle ball, yard ball, generic ball). In this case the drag is significant compared to the weight of the ball. Don't hurt you arm, but you will notice that throwing the ball harder and harder, will eventually lead to no great increase in the flight speed.

Therefore, the maximum speed is when the ball leaves the pitcher's hand under normal conditions of environment.

Sincerely,

Tom "YardBall 2000 Champ" Cull

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