## 29 July 2012

### Sabres and Bikinis

One thing I truly enjoy about the Olympics is the opportunity to watch sporting events I seldom see -- and seldom seek.  Much of my viewing right now is governed by what my two young daughters want to see.  They love watching the female competitors, especially the gymnasts, the swimmers, and, just recently, the beach volleyball athletes.

My older daughter, age 8, loves watching beach volleyball, and we've seen a good bit of the preliminary action. She had fun rooting on Misty (May-Treanor) and Kerri (Walsh) as they beat Australia.  We also saw Italy beat Russia.  My daughter was rooting for Greta (Cicolari) and Marta (Menegatti) as much as she rooted for Misty and Kerri!  Ball speed was given a few times, and I thought I'd do some calculations because I've not played with volleyball much, though I have seen the drag coefficient curve for a volleyball.

A beach volleyball weighs about 2.65 N (0.595 pounds).  One serve by one of the Italians was clocked at 60 km/hr (16.67 m/s or 37.28 mph).  That speed corresponds to a Reynolds number a bit greater than 240,000 -- almost past the drag crisis.  The drag coefficient at that speed is a tad larger than 0.11.  The initial drag force on the Italian's serve was roughly 0.69 N (0.15 pounds), or 26% of the ball's weight.  The buoyant force on the ball, which is due to the fact that the ball's volume displaces air, is only about 2.3% of the ball's weight.  Serves that have very little spin look to have a "knuckleball" effect, meaning they wobble due to varying asymmetric shedding of the boundary layer, which comes about because of the smooth and rough areas on the ball.

A newcomer to beach volleyball, I found the competition fascinating.  Athletes have sophisticated strategies for play, and they have amazing reflexes.  It boggled my mind how they were able to get to some of the smashes!  I also saw quick reflexes on display in a sport with which I am even less familiar than beach volleyball -- fencing.

The men's sabre competition was exciting to watch.  Áron Szilágyi of Hungary defeated Diego Occhiuzzi in the final.  I confess that I know very little about fencing.  I was stunned how fast each point was earned -- not the sabre duels I see in movies!  Lightening quick reflexes lead to swift strikes, and I learned that sabre duels are quick because athletes may score with the blade's edge, in addition to the sabre's point.  Szilágyi was clearly the elite of the competition and well-deserving of his gold medal.  I especially like the class he showed after the penultimate point in the final match when Occhiuzzi looked to have a cramp or pulled muscle in his leg.  Szilágyi showed genuine concern for his opponent.  Great sportsmanship!

I try to watch as much of the Olympics as I can, but there are only so  many hours in the day.  I also have a life outside sports!  Today was about spending time with my daughters and taking delight in their enjoyment of the London Olympics.  Sabres and bikinis are about as far apart as one can get, but the athletes associated with each taught me something new about their respective sport.

#### 1 comment:

1. You're doing a very good job. Keep it up. I can go to your blog and catch up on some of the events I have missed.