Well, it would obviously work much better if I used better software and hardware instead of try to frame count using an iPhone and free websites.

Before today I had guessed I was slinging in the mid 90’s mph. 

Today I tried to throw hard while still being accurate.  Frame counting the video afterwards and then adjusting the average speed to starting speed, showed pitch speeds of 94 mph to 100 mph. 

Might be wrong, but sounds reasonable.

Was happy with accuracy too. Even tossed a few baseball at the end to compare them to the tennis balls.  Was a fun day!

Feel free to check the velocity. Throwing distance was 60 feet, 6 inches from the fence….measured with a tape.

https://youtu.be/geD5Z6l8omM?is=hCk4fVUxU46CtvMl

Definitely having fun now that I can mix slinging my baseball background.  Ready to pitch to a real batter…tennis balls of course as still a little wild. Just got to find someone brave and dumb enough!

Thank you so much for checking!  Totally agree with average speed. I count 16 frames and get 77.5 mpg too. 

I don’t see hard data either on tennis ball speed reduction. I don’t know it is correct but I feel like it might be.

Intuitively I would imagine the tennis ball is designed to slow significantly for safety reasons of course but I think also very likely for playability too.

A tennis court is essentially the same length as baseball pitching distance. The problem is the tennis ball is coming off the server’s racket at 120 mph vs a MLB pitcher thrown ball speed of 95 mph. If the tennis ball did not slow down significantly it would be un-hittable I would think.

So reduce the tennis ball speed from 120 mph to 95 mph in 60 feet distance. That is 21% reduction in speed in 60 feet.  Honestly 95 mph is still pretty hard to hit.  A 30% reduction from 120 mph serve would mean trying to hit a 84 mph ball….which is more reasonable to accomplish.

So I don’t know 30% speed reduction is true….but seems like it kind of could be.

Anyone have the real answer for how much a tennis ball slows in 60.5 feet distance?

If we have an average velocity of 77 mph (~34.5 m/s) over the 60ft 6" (18.44 m) and assume a terminal velocity of the tennis ball of 25 m/s, then this is the velocity drop over the thrown distance. The initial velocity is a bit over 40 m/s which is about 90 mph.
If the terminal velocity of the tennis ball is more at 21 m/s, as some sources suggest, then the velocity drops even more which means that your initial velocity was a little bit higher.

oops. the graph I put up disappeared. I fixed it.

@Bandit I was just trying to point out that the drop in velocity is very fast, nothing about our relative speeds.
I get about 30% drop (over 20m) between the release speed and average speed, so that is in line with what you calculated. You could have been hitting 100mph with an average speed of nearly 80mph.

Wow this is great data! Crazy that it drops speed so much faster than I thought. If only racquet balls were a little heavier and cheaper, they'd be a much better practice ammo.

That's three different sources with effectively the same outcome, pretty well confirmation there barring some much more in-depth tests which are probably not worth the effort(and will probably show the same result).