The Physics of the
Pinewood Derby Book

The Virtual Racing CD


Select Individual Items
Axle Polish Compound
Vary Car Parameter A


Step Size & min-max steps
Suppose when you are designing your car you are interested in how much difference it makes at the finish line on a particular track if you have various values for the coefficient of wheel/axle friction. (Note you can have other friction, but wheel/axle is the load bearing part that makes 90% of the total). So you click on the Brett Bullet car and pick the MU parameter to study. You want to vary the MU value for values larger and smaller than your current value of 0.06. So you click on the [Step size & min-max steps] tab. Suppose you choose 5 steps less and 5 steps more than the current value with each step size set at 0.01. Then hit [Step and Run]. You can see that taking MU to near zero at 0.01 will get you 0.827 car lengths faster to the finish line while increasing MU by this amount will make you about that much slower.


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