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1-D kinematic Problem

  1. Sep 3, 2012 #1
    1. The problem statement, all variables and given/known data
    Determine the average number of g's experienced by someone abruptly coming to rest from an initial velocity of 30mph (such as in a car crash). Take the distance involved in coming to rest to be 1 m.

    2. Relevant equations
    V=Vo+at
    ΔS=VoT+1/2at^2
    V^2=Vo^2+2aΔS

    3. The attempt at a solution
    t=?
    a=?
    Vo= 30 mph
    V=?
    ΔS=?

    Thank you, I'm really stuck and any help will be deeply appreciate it.
     
  2. jcsd
  3. Sep 3, 2012 #2

    lewando

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    Gold Member

    You know Vfinal = 0 and ΔS (change in distance) = 1m. does that help?
     
  4. Sep 3, 2012 #3
    so...
    t=?
    a=?
    Vo= 30 mph
    V=0
    ΔS=1m

    V^2=Vo^2+2aΔS
    0=(30mph)^2+2a(1m)
    which resulted in a= -450mph

    I know g= 9.8m/s ... so I'm assuming I have to change the -450mph to m/s by diving -450/3600s = 0.125m/s

    I really dont know what to do next or if I'm in the right track...
     
  5. Sep 3, 2012 #4

    lewando

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    Gold Member

    a should be in units of m/s2

    (convert mph to m/s)
     
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