"Tennis balls, my liege"
King Henry: "What treasure, uncle?"
Exeter: "Tennis balls, my liege."
William Shakespeare, Henry V, act 1, scene 2
Using that quote as a springboard, I interrupt my considerations of Shakespeare's plays to visit the ever-so-tangentially-related topic of tennis. The other day I recorded myself throwing tennis balls, serving tennis balls, and throwing baseballs at distances of 10, 15, 20, and 25 feet. Knowing the footage was shot at 30 frames per second (I did confirm that by recording a stopwatch) allows me to calculate the speed with reasonable accuracy.
The slides below can serve as an example: The ball traveled 20 feet (note the measuring tape) in 5 frames (1/6 of a second), equating to 120 feet per second (20*6), or about 82 mph (120/1.467).
Here is a summary of the results:
And here's the spreadsheet, with all the hard data:
It's astonishing to think professional baseball pitchers can throw twice as fast, or that elite tennis players regularly serve 50% faster - and both with far more accuracy than I'll ever have!
Obviously, this test not flawless - it does not address aim (a tennis serve is worthless if it doesn't land in the service box), and footage with more frames per second would increase the precision of the math - but it gives a pretty good estimate.
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