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Homework Help: Double check this problem/solution I made?

  1. Mar 1, 2009 #1
    I have to create my own physics question for homework which combines momentum/collisions with another unit (I chose forces/friction). Then I have to solve it.

    1. The problem statement, all variables and given/known data

    Lewis Hamilton is testing his new McLaren when suddenly he misses the pitlane break point and crashes into Kimi Raikkonen's Ferrari at 280 km/h. If Kimi was driving at 50km/h and the impact lasts for 0.3s and the coefficiant of friction is 0.3:
    A) How far does each car slide?
    B) Supposing that humans cannot survive over 80Gs, do either one of the drivers survive?

    2. Relevant equations

    impulse
    p=p`
    F=ma

    3. The attempt at a solution

    280km/h = 77.7 m/s
    50kkm/h = 13.9 m/s
    m1v1 + m2v2 = m1v1` + m2v2`
    605(77.7) + 605(13.9) = 605(v1`) + 605(v2`)
    V1` = 91.6 - V2`

    v1 - v2 = v2` - v1`
    77.7 - 13.9 = v2` - (91.6 - v2`)
    V2` = 77.7 m/s
    v1` = 13.9 m/s

    //KIMI RAIKKONEN SLIDE
    vf^2 - vi^2 = 2(a)(s)
    a = -Ff / m
    a = -ug
    a = 0.3(9.8) = -2.94
    0^2 - (77.7)^2 = 2(-2.94)(s)
    s = 1026.75m

    //LEWIS HAMILTON SLIDE
    vf^2 - vi^2 = 2(a)(s)
    a = -Ff / m
    a = -ug
    a = 0.3(9.8) = -2.94
    0^2 - (13.9)^2 = 2(-2.94)(s)
    s = 32.85m

    //G FORCE FOR LEWIS HAMILTON
    v1 = 605(77.7) = 47008.5
    v1` = 605(13.9) = 8409.5
    change in momentum = v1 - v1` = 38599
    38599 = F * t
    38599 = F * 0.3
    F = 128663
    G force = F / 9.8 = 13128.9

    //G FORCE FOR KIMI RAIKKONEN
    v1 = 605(13.9) = 8409.5
    v1` = 605(77.7) = 47008.5

    change in momentum = v1 - v1` = -38599
    -38599 = F * t
    -38599 = F * 0.3
    F = -128663
    G force = F / 9.8 = -13128.9





    Okay! Now the thing is, those G forces looks REALLY high. I mean obviously the crash is going to produce a big number but I was guessing it would be between 75-200. Right now as you can see it's in the thousands.

    Did I miss something?

    P.S. I realize that this is obviously missing like a million real-world factors but it's for a high school physics class so no need to make it excessive with stuff we have not learned yet.

    Thanks!!
     
  2. jcsd
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