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Mousetrap vehicle (please reply today )

  1. Jan 6, 2012 #1
    Mousetrap vehicle (please reply today!!)

    My first post :)
    Hi everyone! I'm in Science Olympiad working on mousetrap vehicle, but there's a problem... My lever arm is as long as I can make it that the vehicle can support so I can even attempt to go the entire ten meters but it goes down WAY too quickly. I can only go between 6-8 meters because of this. On YouTube I've done quite a bit of research (I used the word quite xD) and all of the cars that do well have lever arms that go down over a relatively long period of time. Why do you think mine wont? Actually, I have a competition in 8 hours (7:30 tomorrow my time) and have been testing tonight. Please help me asap!! Thank you so much :)
  2. jcsd
  3. Jan 6, 2012 #2

    Simon Bridge

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    Re: Mousetrap vehicle (please reply today!!)

    Welcome to PF.
    You know how these things work right? You are converting the energy stored in the mouse-trap spring into kinetic energy in the car - the spring will release the same amount of energy no matter what lever-arm you use so you need to think about the role the lever part plays. eg, if you accelerate too fast the wheels will skid, wasting energy.

    How fast the arm moves will depend on the moment of inertia of the arm, the weight/drag effect of the cart, and the strength of the spring.

    Some of the energy from the spring will go to turning the wheels ... so you need to consider the advantages of big vs small wheels.

    General tips and tricks.

    Since you are building for distance you want to minimize your power output.
    You have already maximized your lever arm - next step is to adjust the pulley ratio by increasing the axle-to-wheel ratio. Fix a sewing bobbin to your axle.
    Last edited: Jan 7, 2012
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