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First moment

Q: On page 53 of Racquet Service Techniques, it states, “first moment (or static moment) is the weight of the racquet multiplied by the distance of the balance point from your hand.” Aren’t you supposed to multiply by the distance from the balance point to the butt end of the racquet?

A: That would be the case if you were to hold the racquet by the butt cap. Holding the racquet creates a pivot point around which the mass of the racquet tries to rotate, due to the pull of gravity. When you are holding a racquet handle in the normal fashion, the pivot point is considered to be roughly under the first knuckle of your index finger, which for most players is about four inches up from the end of the butt cap. Conveniently, this pivot point is also the one used by the Babolat Racquet Diagnostic Center (RDC) when measuring swing weight.

From the June 2004 issue
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