**Greatest Acceleration Racer Answer**, Posted by John Valente on 10-14-2017:

The performance of the project in the Greatest Acceleration Racer will be based upon the average acceleration of the project within the specified dimensions of the course (0.25 m through 1.25 m). A motion detector will be used to generate x-t and v-t graphs for each run. Once a run is complete, the graphing tools can be used to identify and display the numeric values for points of interest. The time at which the racer has moved 0.25 m and 1.25 m from the motion sensor will be determined from the x-t graph. These time values will be located along the v-t graph (as close as possible in some cases) and the corresponding velocity values will be obtained. A sample run for a wind-up toy is shown below. However the length for this trial was only from 0.25 m to 0.60 m. Four data points have been identified - time at position 0.25 m, the corresponding velocity at the closest possible time to the position value, the time at the finish line (0.6 m for my sample run), and the corresponding velocity for the previously mentioned position value.

*To see the data referred to, click on link below. * *Can't post it here in the forum due to file size limits.*

Here's a link to the graph/data

With this data, the average acceleration value may now be determined. Since we are only interested in the greatest average acceleration, we can determine it using change in velocity divided by the change in time. This data can be extracted from the graph displayed above The calculation can then be performed with the aid of a calculator or in a spreadsheet. On competition day, the latter will most likely be used as it will be able to perform the calculation as data is entered. This approach would apply to all racers regardless of whether the vehicle moved with a constant acceleration or not.

From Dave Bandel, Judge of this event

John Valente, Physics Olympics Committee