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Homework Help: Finding f_max of an impulse.

  1. Aug 29, 2009 #1
    1. The problem statement, all variables and given/known data
    In the figure , what value of F_max gives an impulse of 6.8 Ns?
    http://img76.imageshack.us/img76/1782/09ex05.jpg [Broken]

    2. Relevant equations
    Integral of F with respect to time equals impulse

    3. The attempt at a solution
    I tried doing two things, and they were both wrong.

    First, i tried the integral of F with respect to time from 0 to 8 = 6.8.
    Ft from 0 to 8 = 6.8
    F(8) - F(0) = 6.8
    F = 6.8/8
    F = 0.85
    I realize that is wrong though, since the picture they give us isn't of constant force.

    So then I tried using the area of a triangle:
    Area = (1/2)b*h
    Area = (1/2)*8*h
    4h = 6.8
    h = 6.8/4 = 1.7

    So I entered 1.7 into the website, and it said it was wrong. If that didn't work, I have no idea what else I could do to find it.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Aug 29, 2009 #2
    Note that the units on the time axis are miliseconds. Hence, 4x10^-3*Fmax==6.8, Fmax==1700N.
    Last edited by a moderator: May 4, 2017
  4. Aug 29, 2009 #3
    Oh, wow I didn't notice that at all. I'm too used to it always being in seconds I didn't even think about looking at that. :p

    Thanks a lot for your help!
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