MadSci Network: Physics

Re: Research on surfaces & traveling of a matchbox car

Date: Mon Nov 20 09:56:22 2000
Posted By: Arnold Anderson, Staff, Tribology/Friction systems, retired (Ford Scientific Laboratory)
Area of science: Physics
ID: 974320072.Ph

You asked about what surface provides maximum speed for a matchbox car.  
My son suggested that the fastest surface is a vertical surface.  He was 
correct, of course, but that was not the answer you wanted.

To have speed and distance traveled a maximum, the frictional losses have 
to minimized.  The surface that the car rolls on does contribute to some 

One of these is hysteresis loss.  If you pedaled a bike over soft soil, 
you know what this is like.  To make hysteresis losses small, the rolling 
surface should be hard, smooth, and flat.  Generally, the lower the 
deflection, the lower the loss.  

Some materials have lower hysteresis losses than others.  High hysteresis 
materials (like soft soil or putty) have a dull, dead sound when hit.  Low 
hysteresis materials (like steel or glass) ring like bells.  If the 
material is hard enough, hysteresis losses will be insignificant.  For 
example, railroad wheels on a steel rail have rolling frictional losses 
around 0.001.  Automotive tires on concrete are ten to twenty times more 
than this.  A bike on soft soil is much higher yet.

Another source for loss occurs when the surface introduces steering 
error.  An irregular, uneven surface may cause side slippage of one or 
more tires as they roll.  If a channel is used to control the rolling path 
of the matchbox car, the channel shape is important.  It should guide the 
wheel without introducing side slippage or vibrations.

In brief, what you need is a hard, smooth, clean, dry, and non-sticky 

Some references follow that you and your son may find useful.

Pinewood derby racing

Rolling friction

Matchbox school project

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