MadSci Network: Engineering |
Hi - I don't know exactly what constraints you have for your testing, but the easiest way to make it "stop on target" would be to run a series of tests with the car (+ or - load of coke bottle) beforehand. Wind it up with a defined amount of tension in the rubber band and see how far it goes (25 "turns" for example). For each distance I'd recommend running the car 3 - 5 times, so you can determine the range of distances you get for the number of "twists" in the rubber band. You should be able to make a plot (with error bars) demonstating number of twists of the rubber band and how far the car travels. When you need to make it stop on a target of defined distance, you can then look at your plot and determine approximately how many twists of the rubber band you would need.
There will be some confounding factors with this method. If the rubber band streches with use, your numbers will probably not remain true, so you might want to consider changing the band often during your experiments.
Hope this helps..
L. Bry, MadSci Admin
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