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Re: [Phys-l] Pinewood Derby Car Weight....



At 10:56 PM 2/24/2007, Zeke K., you wrote:

> 1. Moving the extra mass to the back of the car won't help because
> every point of the car drops through the same vertical distance
> between the beginning and end of the track.

Surprisingly, this isn't true.

Because the car rests at an angle and finishes flat, the back of the
car undergoes a slightly greater change in height than the front.

> 2. Taking one front wheel out of the game may help a little but it
> also runs the risk of having the car swerve toward the side with the
> functioning wheel and may take it off the track, causing
> disqualification.

Most of the tracks have wheel grooves that keep the car going
straight. However, if the wheels hit the edge of these grooves,
they lose lots of energy. Given that, it is absolutely essential that
the car drive straight. Further, it is also very important that
the four wheels are directly exactly forward. Any racking of
the wheels will eat energy out of the motion.

Marc "Zeke" Kossover
The Jewish Community High School of the Bay

Here's another little go-faster tip:
though most competitors use graphite powder to dust the axles,
a winning strategy is to PACK the axle space with compacted
graphite powder, then have the axle penetrate the compacted dust
so that it has a continued graphite bearing surface.

Parents who are as competitive as baseball moms might want to
consider replacing those tail-end lead weights with tungsten cubes....
<http://www.maximum-velocity.com/>


Brian Whatcott Altus OK Eureka!