## Evidence of Speed It’s possible sometimes to gather information from indirect evidence about an animal. The footprint of an animal may tell many things. A biologist named R. McNeill Alexander developed a formula to calculate the speed of a living animal from the trackways (series of footprints) that the animal left behind. His formula used the stride distance and hip height to calculate the speed.

A TRACKWAY can be divided into three sections: The PACE, the distance between the right and left foot; the STRIDE, the distance between two successive steps (right-right, or left-left); and the GAUGE, which is the width of the tracks, telling how close the legs were together. Measure toe to toe.

Materials Scientific Calculator Meter Stick Timer Place to walk or run where foot prints show Procedures:

1. On sand (or other good footprint area) measure out 5 meters.

2. Walk or run across this area timing how long it takes to go the 5m.

3. Measure your foot length and multiply by 4 to get the hip height.

4. Measure your stride from the footprints.

5. Calculate your speeds (on data table below).

6. Compare the two methods of calculation

 Data Table: Distance covered 5 meters Time seconds Measured Speed = meters/second Foot Length meters Hip Height (4 times foot length) meters Pace Length meters Stride Length meters

Formula for direct measurement:

speed = =                                                     __________meters/second

Formula for Indirect measurement: (Alexander's)  NOTE: g= 9.8 meters/second²

speed=                                             ___________meters/second

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