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Racing Hot Wheels cars

  1. Sep 11, 2007 #1
    I'm interested in the physics behind racing Hot Wheels cars. When you release the cars from an incline, what makes some cars go faster than others? What would be the most important factor of a fast car (ex. weight, aerodynamics, etc.)? How could I modify a car to go faster? Thanks!
     
  2. jcsd
  3. Sep 11, 2007 #2
    Increasing the mass and reducing the area of car exposed to the air would increase the "terminal velocity" of the car down the plane, (If that is the correct term for this situation.) Because all objects fall at the same rate, increasing the mass would not decrease it's acceleration. Also reducing the friction between the axle and chasis will enable a greater top speed.
     
  4. Sep 11, 2007 #3
    Would it make a difference if the weight was on the front or back of the car?
     
  5. Sep 11, 2007 #4

    Danger

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    Not for that kind of machine, to an appreciable degree. Loading one set of 'axles' more than the other would increase the frictional loss on one, but decrease it on the other. When you're dealing with an 'axle' of smaller diameter than a paper clip, I doubt that you could even measure it.
    Believe it or not, I still have a few Hot Wheels cars... 40 years after the last time that I played with them.
     
  6. Sep 11, 2007 #5
    Thanks!
     
  7. Sep 11, 2007 #6

    Danger

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    You're welcome. Bye the by, I would seriously recommend against trying to lubricate the wheels. If memory serves, the 'axles' are about 1/2mm diameter spring steel. That going into hard plastic is about as close to frictionless as you can get for $5. Any lubricant other than graphite or silicone or Teflon would just clog it up. That's the same reason that you can't put oil, including WD40, in the pin area of a lock. It collects dust, which then becomes mud, which eventually becomes cement.

    Just out of curiosity, did any of the other old farts around here have the 'supercharger' for Hot Wheels? That thing gave my cat hours upon hours of excercise.
     
  8. Sep 11, 2007 #7

    DaveC426913

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    I had one. Yup.
     
  9. Sep 11, 2007 #8

    Danger

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    Cool. Our basement was about 35' long, with a concrete floor. I'd hold Snoopy back, launch the car out of the supercharger with about 1' of track, then let him go. I don't think that the car ever hit the wall before he got it. (Although he tumbled into the wall a couple of times after catching the car. :biggrin:)
     
  10. Sep 11, 2007 #9
    Can you all invent an economical configuration using magnets for partial levitation, thus reducing friction/weight of this modified Hot Wheel?
     
  11. Sep 11, 2007 #10

    Danger

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    Of course, but it's gonna cost you.
     
  12. Sep 11, 2007 #11

    rcgldr

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    For pine box derby cars, having the as much weight at the back raises the center of mass on the sloped track, and therefore the car would have a bit more gravitational potential energy, assuming that the track ends up near horizontal for a reasonable distance. I don't know if it's enough to make a difference on a hot wheels car.
     
  13. Sep 11, 2007 #12
    I don't think Galileo would sponsor your crate. On second thought, you're right. Also wear a helmet of uranium.
     
    Last edited: Sep 11, 2007
  14. Sep 11, 2007 #13

    rcgldr

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    Pine box, not soap box. The pine box models are those cars that used to start out as a small block of pine wood, but not you can buy pre-shaped models.

    Regarding soap box cars, one clever idea was to use a electro magnet at the start, but that team got caught as the car kept winning by too much.
     
  15. Sep 11, 2007 #14
    I seem to remember the pine derby in the Boy or Cub Scouts. Can one use permanent magnets oriented relative to the earth's magnetic poles?
     
  16. Sep 11, 2007 #15

    Danger

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    Hmmm... isn't that Grandpa Munster's dragster?
     
  17. Sep 12, 2007 #16

    rcgldr

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    Getting this out of context. The electro magnet was used in soap box derby, the wooden equivalent motorless go-karts. Since the starting gate that dropped forwards was made of metal, a father and son team decided to get an advantage by using an electrical magnet that would use the power of the gate dropping to give the kart an initial forwards boost. Problem was that it worked too well, and it was obvious by the end of a run that something was going on, since it was so much faster than the other soap box carts.
     
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