Computing MPH

[Greg Hermann]

At 10:00 AM 8/27/01, steve ravet wrote:
>You need Gs and time.  The first derivative of distance is velocity, and
>the second is acceleration.  If you take the acceleration info,
>numerically integrate w/ respect to time, you'll get velocity.
>Integrate one more time and you'll get distance.  It's easy to do:
>
>Take each acceleration data point, multiply by the sampling interval.
>Sum these up to get your velocity.  If Gs are in ft/sec^2, you'll get
>velocity in ft/sec.  There are other methods of mumerical integration
>that are more accurate, you could find them in a starter calculus book.
>A faster sampling rate will improve the accuracy of this calculation but
>it probably doesn't matter too much if you only want trap speed (vs
>speed at other points on the track).
>
>--steve
>
This approach is as accurate as you are going to get for any given sampling
rate. dt is actually approximated by delta t (the sampling interval),
rather than being infinitely small, as is the "theory" in calculus--

Greg


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