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Homework Help: Impact force (distance & time after impact unknown)

  1. Jul 22, 2012 #1
    1. The problem statement, all variables and given/known data

    A vehicle falls 20 mm back onto a smooth steel track after going over a bump. It has polyurethane wheels. Young's modulus is known for both wheels and track materials. What is the force exerted by the vehicle onto the track as it lands?

    2. Relevant equations

    F = mdv/dt

    KE = (ma^2)/2

    F = KE/d

    3. The attempt at a solution

    I've looked long and hard for a solution to this but all I found were equations (such as the ones above) that require either a pre-known time value for the collision or a pre-known value for distance travelled after impact.

    How can an impact force be calculated simply by knowing material properties, mass of falling object, and distance of fall?

    Last edited: Jul 22, 2012
  2. jcsd
  3. Jul 25, 2012 #2


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    Gold Member

    I'm not familiar with Youngs Modulus but since you haven't had an answer...

    Presumably the youngs modulus can be used to work out an equivalent spring constant for the combined wheel/track. You know the energy compressing it so you can work out the distance it's compressed???
  4. Jul 26, 2012 #3
    Thanks. I've since found a couple of equations for impact stress and deflection, based on strain energy.
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