RACQUET SCIENCE — using physics to help select a racquet
Derivation of the Shoulder Pull Formula
Shoulder Pull is the centripetal force, in Newtons,with the shoulder being a distance R (= 0.61 + r/100) meters from the racquet mass center. The Shoulder Pull force, measured in units of Newtons (1 Newton = 0.225 lb.) attributable to the racquet alone is derived from the Work formula and the general formula for centripetal force (centrifugal force). See the accompanying remarks. A complete description of all variables used in this derivation follows at the end.
| I | = | moment of inertia (swing weight) of racquet, in kilograms·centimeters² |
|---|---|---|
| b | = | mass of ball, in kilograms |
| d | = | distance from axis of rotation to impact point, in centimeters |
| s | = | ball velocity, in meters-per-second (positive is away from player) |
| r | = | distance from axis of rotation to mass center, in centimeters |
| v | = | linear velocity of mass center, in meters-per-second |
| M | = | mass of racquet, in kilograms |
| c | = | coefficient of restitution of the racquet/ball system |