One group of my students did the tired weight project for a cooperative
learning/demonstration project in my physics class. They used a hand truck with
pneumatic tires. These wide tires gave a good footprint from which to
calculate the area. They also put masses on the hand truck to increase the total
weight. They also tilted the handtruck to a position where it seemed to be
balanced which placed all of the weight directly onto the tires. They were
disappointed because the weight they calculated using the area, the pressure and the
fact that there were only two tires was off by a factor of 2. I think they
tried this at home with their car and got good results. My feeling is that
something is wrong with the theory. They used an accurate and calibrated tire
gauge. They repeated the experiment a number of times and kept getting the
same results.
R. Clements Rclem616@aol.com
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