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Dealing with mass, acceleration and velocity

  1. Sep 27, 2007 #1
    1. The problem statement, all variables and given/known data
    Problem: A person wearing a seatbelt can withstand an acceleration of -0.030 m/s2. How thick should barriers be to safely stop a car that hits a barrier at 110 km/h?

    2. Relevant equations

    3. The attempt at a solution
    I so far have no attempt. I do not know what sort of formula can be used or what type of problem it is ie. constant velocity, displacement, friction so on. The sort of help that I need is a possible formula you might know of or even what kind of problem this is.
  2. jcsd
  3. Sep 27, 2007 #2


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    Gold Member

    I think the key formula is, with a=acceleration, v=initial speed, t=time and s=distance,

    [tex]s = \frac{1}{2}at^2 + vt[/tex]

    Assume the barrier applies a constant deceleration.
  4. Sep 30, 2007 #3
    Thank you Mentz114. That is very helpful! I'll try the problem using that formula now. Thanks again!
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