# A COMPARISON OF TWO FUNCTIONS REPRESENTING VELOCITY OF A HUMAN BODY SUBJECT TO PASSIVE DRAG

• Roozbeh Naemi
• Ross H. Sanders
Keywords: swimming, glide, passive drag, curve fitting

### Abstract

The purpose of this study was to compare the goodness of fit of two functions representing horizontal velocity of a human body subject to passive drag. Hyperbolic and exponential functions were fitted to the horizontal velocity data of three glides following push-off from the wall of five swimmers. Measures of goodness of fit included root mean square errors (RMSE), and the coefficient of determination (R2). The hyperbolic function provided a better fit to the actual values of velocity, provided a closer match to the initial velocity, and predicted better the velocities beyond the fitted interval than the exponential function. It was concluded that for the swimmers and range of glide velocities tested, drag was closer to being proportional to the square of velocity than a linear function of velocity.
Published
2008-03-25
Section
Methodology
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