Ping-Pong Ball Boys

January 29, 2014

Angular Momentum Conservation and the Forehand

Ever notice how when a figure skater is spinning, if she brings her arms in she spins faster? Here's an explanation of that; it's the law of angular momentum conservation. Here's an article that explains this.

The laws of angular momentum apply to both figure skating and table tennis. What this means is that you can rotate faster with your arms in. On the forward swing you have to extend the arm some to get power, especially if you use a Chinese-style straight arm forehand loop. But there's no need to extend the arm during the backswing, and it just slows you down. So in theory, table tennis players should bring their arms in during the backswing in fast rallies so the backswings are quicker. What does the videotapes tell us?

Here's a video of Zhang Jike (1:55) and his forehand loop during fast multiball. Compare how far his racket is extended at contact to where it is during the backswing, and sure enough, he brings his arm in during the backswing. Here's a video of Ma Long (32 sec) showing his forehand in slow motion, which makes it even clearer. Again, compare the racket's position at contact with where it is during the backswing.

But now we look at a video of Timo Boll (2:12), and see a discrepancy - he holds the racket out about as much during the backswing as the contact point. But there's a reason for this - Boll uses a European-style loop, with his arm more bent, and so never extends his racket that far from his body. Compare to Zhang Jike and Ma Long and see the difference.

How about hitters? Here's a video (51:06, but you only need to watch the first 7 sec) that shows two-time world champion pips-out penholder Jiang Jialiang hitting forehands. Note how he drops the racket tip down for the backswing, then extends it sideways during the forward swing? This quickens the backswing.

An extended version of this might become a Tip of the Week.

The Growing Significance of the Backhand Loop

Here's the article from Table Tennis Master. Somehow I missed this article when it came out a year ago.

U.S. Open Blog

Here's another blog entry from Dell & Connie Sweeris, co-chairs for the 2014 U.S. Open in Grand Rapids: "My Favorite U.S. Open Experiences"

Zhang Jike Wins Chinese Team Trials

Here's the article and video (36.43) of the final against Ma Long. He started with a loss to Liang Jingkun, then followed that with ten consecutive wins, including wins over his main rivals on the team, Ma Long, Xu Xin, and Fan Zhendong.

Westchester Joins North American Tour

The Westchester Table Tennis Club, which runs monthly 4-star tournaments - something no club has ever done - has joined the North American Tour. There'll be a press release at some point on this and other aspects of the Tour, but for now here is the current list of tournaments in the Tour (which includes links for other info on the Tour). Others will be listed as the paperwork is complete. Special thanks to Bruce Liu, who organizes the Tour.

Ping-Pong Ball Boys?

Here's the cartoon!

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