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Homework Help: Tricycle problem

  1. Jul 17, 2007 #1
    Mechanics problem - Tricycle?


    On the tricycle above, the pedals are locked to the wheel.
    What happens when the Force pulls in the picture above and why?

    - I think that the wheel will spin the other way, making the tricycle drive backwards. Is this correct?

    Thank you for the help
  2. jcsd
  3. Jul 17, 2007 #2


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    Welcome to PF, Emant, but I have no idea what the hell you're asking. To start with, if this is homework you're in the wrong section.
    Anyhow, the force applied to a cycle's pedals is semicircular, not linear. The force applied to the road by the tire is linear, but in the opposite direction to what you've indicated by the arrow. This is a confusing post.
  4. Jul 17, 2007 #3
    The possibilities seem to be:
    - The friction is low, and the whole bike will slide forward (despite the front wheel turning a bit in the backward direction).
    - The force is low, and so friction will prevent anything from happening.
    - Both the force and the friction are high, and so the whole bike will start to pivot over the point where the front wheel touches the ground, falling upside down.
  5. Jul 23, 2007 #4
    What do YOU mean by a *semicircular* force????? I've never heard of such a thing.

    As for the tricycle, the solution can either be exremely difficult or extremely simple depending on the analysis. I don't think the answer is intuitive unless you actually try it with a tricycle.
  6. Jul 23, 2007 #5


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    Depends greatly on the traction of the wheel on the ground.
  7. Jul 23, 2007 #6
    Assume there is just enough friction so that the wheel can rotate without slipping. The more you think about this proble, the more difficult it will be to solve. Think simple!
  8. Jul 23, 2007 #7


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    Personally, I don;t see how it could move backwards at all. You pull on the pedal, and the tricycle will move forward.

    You can't possibly pull the pedal forward and have the tricycle move backward. My point about the traction is that you won't be able to pull the tricycle forward without overcoming the static friction on the ground.
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