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Homework Help: Find the size of the force due to wind and rolling friction

  1. Feb 23, 2008 #1
    [SOLVED] Force Problem

    The total mass is 2300kg (weight = 5072lbs). Find the size of the force due to wind and rolling friction when the van speed is 42.17mph (1mph= 0.447m/s).

    This is the graph: http://capa-new.colorado.edu/msuphysicslib/Graphics/Gtype12/prob09a_1004minivan.gif" [Broken]

    F = ma

    a = (speed 2 - speed 1)/(Time 2 - Time 1)

    Converted mph to m/s: a = (26.82 - 18.85)/(23) = 0.3465 m/s^2

    Now F = (2300*0.3465) = 797 N

    What did I do wrong?
     
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Feb 23, 2008 #2

    Dick

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    You didn't do much wrong. Your graph looks a bit nonlinear, but I don't see how they would expect you to read much more than a rough estimate off of it. Is that really the statement of the problem? 42.17mph!??? Four decimal places?
     
    Last edited: Feb 23, 2008
  4. Feb 23, 2008 #3
    Take the slope over the entire range of the graph.
     
  5. Feb 23, 2008 #4
    That's what I'm assuming... they gave me the weight in lbs. do I need to incorporate that into my equations in any way or is that just unnecessary/useless info.
     
  6. Feb 23, 2008 #5
    ohhi thanks a lot !
     
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