The Ball Bounce at 10,000 Frames Per Second

[johnyandell]

Let's discuss Paul Hamori's article, "The Ball Bounce at 10,000 Frames Per Second"

[doctorhl]

Very informative. and fascinating as the pros can so quickly adjust to bounce variations due to incoming flight/spin characteristics, court surfaces, and wind/ humidity conditions. As a sport science nerd, two questions come to mind:

1.How much would the data change when the ball knap captures moisture in very high humidity conditions? Club tournament play in very high humidity conditions in which spin pulls out hard court knap fibers, long sets without changing balls, and balls held in sweaty pockets (no ball persons) often required stroke variation or -5 pounds or more adjustment in string tension.

2.How much variation is there in skid bounce between a traditional slice and the Federer knife slice? That difference seems large enough to affect the hitter’s timing. I have experienced the difference, but have never seen it captured on film and also wonder about the incoming/outgoing rpm differences between the two.

[paulhamori]

In reply to doctor.rhl: I think that the more the balls fluff up, and become moist, the slower they travel and the slower they spin. Additionally they would have more friction on the court, losing more speed with the bounce. My instinct would tell me they also will pick up less additional topspin through the bounce although John Yandell may have actually studied this and have further insights.

I am a student of the Roger Federer slice myself–a thing of beauty to behold. No question his slice differs from the average pro slice in that it is harder, straighter, with more rotation, and better placed. Typically he goes for a short slice around the service line or just beyond. This is particularly effective to people with a two-handed back hand as they have to get down terribly low in order to field the shot. I think it's fascinating that this shot is effectively removed from his arsenal against his chief rival Rafael Nadal. I speculate that if Rafa had been a right hander thus allowing the cross court backhand slice into his two-handed backhand, he would've posed no real problem for Federer. But because of the net height down the line(and Rafa's incredible ability to run around the backhand) it is impossible for Roger to slice this ball into the Nadal backhand down the line–effectively removing it from the arsenal. And the rest is history as we all know. Thanks for your comments and support, Paul Hamori

[doctorhl]

Dr Hamori: Thanks for the interesting info. If you private message me, I would like your thoughts on vision principles and ball flight characteristics regarding another particular racket sport.

[ten1050]

Dr. Hamori,

Great articles on the ball bounce. I must complement you again on your outstanding book. Your advice has been invaluable, especially the concept of closing one’s eyes on hearing contact with the ball. With considerable practice, I have been able to perceive contact in an astonishing manner. Even when just hand tossing balls to others, I can perceive an amazing after image of the ball and racket head. Like yourself, I have played tennis for over half a century and have read hundreds of tennis books, your book is one of the finest I have ever encountered.

Sincerely,

Norman Ashbrooke