Reduce the probability of inconsistent surfaces You must think
'small' for a second. Very small. super small Let say for example
that you needed to sand down the top of your pinewood car before
painting it. Ok You sand it down with progressively finer sheets
of sandpaper until it is really smooth.
NOW, if you look at the the sanded area with a magnifying glass,
WHOA! it would still have all sorts of ridges, low spots, high spots,
mountiains, craters and other 'not so smooth' areas. While this
is ok for PAINT, it's coefficient of friction would be very high.
How could you reduce the coefficient of friction
withough sanding it further? Well since we know that The amount
of Friction is Independent of the amount of surface areas being
'rubbed together' What would happen if we were to find the BEST
looking area (the smoothest area) and cut the rest of it away. There
would be LESS surface area now, which does not matter anyway, frictionally
speaking, BUT the QUALITY of the remaining surface will have more
consistency to it. Less variables. Less mountains, valleys, ridges
and craters. SO, without further sanding, we have reduced the coefficient
of friction to it's lowest possible value. ---->>>
OK, I see, but what does that have to do with the axels ?? and
why is my car cut in half now?? First off - it's just an example
to show you that no matter how much you polish your axels, there
will still be scratches, bumps and ridges that will interfere with
the tire and that simply by eliminating the majority of the axel
surface, you can increase the QUALITY of your axel surface that
actually contacts the wheel.
If you simply polish your axels - you may have 50 imperfections
which will influence the coefficient of friction in a negative manner.
By eliminating 80% of the axel from the equation, you could ultimately
reduce that to only 10 imperfections, which would give you a much
more consistent coefficient of friction value because now you only
have to worry about 10 little bumps or scratches, instead of 50.
LESS area - LESS problems to deal with. Of Course we are looking
at each axel under a magnifying glass in order to acheive desired
Axel modification techniques are fully explained in the DVD for
you to see
Just a Side Note : since we are trying to REDUCE the Coefficient
of friction The coefficient of friction also varies with temperature.
Looking at this graph (detail provided by Nanoscale
sliding friction versus commensuration ratio )
The relation between c and temperature we can see that for a fixed
a/b ratio the c coefficient increases linearly with temperature
(of course this is at the atomic level). As we have discussed before
after your car has broken free from static friction, SLIDING friction
is your next element to deal with. The aformentioned document provides
Observations regarding sliding friction and temperature of the surfaces
at the particle level. Too small to mess with? possibly, but nonetheless,
if as stated, the coefficient of friction INCREASES with temperature
and the obverse is true, the coefficient of friction DECREASES as
the surface temperature decreases, why not look into this? . ------------------------>>
clairity, I present to you this theory. IF one could cool (ie. reduce
temperature of) the axels of your pinewood derby car, would it not
DECREASE the coefficient of friction presently factored into your
friction equation? My thinking is that YES, it would. And, since a
lower coefficient of friction value equates to less kinetic energy
LOSS, this is a very good thing.Therefore, One must explore possible
scenarios for COOLING the axels. At first glance, It may be better
to COOL the actual wheels since they also contact the track, but this
may be simply impossible due to the obvious fact they are rotating,
so by focusing on cooling the axels, one might find yet another way
to make your pinewood derby car faster. We @ PinewoodProfessor.com
are conducting experiments at this time to implement into our VIPER
unlimited Series (using channels to cool the axels) High tech ...
No Im not going to explain it here.