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Impeding a car's velocity by going over a speedbump with a certain height (radius).

  1. Oct 8, 2012 #1
    1. The problem statement, all variables and given/known data
    A car goes over a speedbump, which has the cross-section of a cylinder of radius R embedded in the roadway. If you want a car driving with a speed Vo to be impeded, how large must R be?

    I'm very confused about this problem because we have not discussed the topic in class and I have a terrible book. I want to say that you use the centripetal force equation, but that is for when velocity is constant? I'm not sure... :confused:

    Knowns:
    V initial = Vo
    V final = 0
    mass = m
    Radius = height of the speed bump

    Unknowns:
    Radius

    2. Relevant equations
    F = m(v^2)/R



    3. The attempt at a solution
    Again, I am having trouble and do not know where to begin. I want to learn how to do this; not get a quick answer. Any and all help will be greatly appreciated.
     
  2. jcsd
  3. Oct 8, 2012 #2
    Re: Impeding a car's velocity by going over a speedbump with a certain height (radius

    We need two numbers to better define the speed bump, the radius R and the height of the section of a cylinder. Is it half a cylinder, a quarter? I hope you understand.

    As for impeding the car you need to be more specific. A car with a very stiff suspension will handle the speed bump differently then a car with a very soft suspension. I think we need more information.
     
  4. Oct 8, 2012 #3
    Re: Impeding a car's velocity by going over a speedbump with a certain height (radius

    This is just how my professor operates. He makes us solve variables with other variables rather than numeric values.
     
  5. Oct 8, 2012 #4

    rcgldr

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    Homework Helper

    Re: Impeding a car's velocity by going over a speedbump with a certain height (radius

    A speed bump won't slow down a car much (assuming it doesn't damage the car's tires, wheels or suspension). Perhaps the goal is to find R so that v02 / R translates in to 1 g of acceleration, but even that would not slow down a car much.
     
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