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Homework Help: Help! I've tried for 10+ hours

  1. Sep 23, 2003 #1
    I've tried question #1 on here:
    http://www.pa.uky.edu/~cvj/PHY404G/phy404g98_test1/phy404g98_test1.html [Broken]

    for the past 10 hours, i have achieved getting something relatively close, but i cannot do the algebra to prove t=cosh^(-1) etc etc...

    has anyone done this problem in the past, i know nitrus has a similar one, and i have talked to him, but it was of no use.

    please help me, it is very appreciated.

    thanks,
     
    Last edited by a moderator: May 1, 2017
  2. jcsd
  3. Sep 23, 2003 #2

    krab

    User Avatar
    Science Advisor

    There is a time integral and a distance integral. Did you get those? They are each of the form of the 2 integrals given as hints. Combine and you get

    sqrt(k g sin(theta)) t =

    (1/2) ln((1+sqrt(Q))/(1-sqrt(Q)))

    where

    Q = 1 - exp(-2 k d)

    The big thing with the ln in it is actually equal to

    cosh^-1(exp(kd)),

    though it is not obvious. So you are done.
     
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