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Homework Help: Change in water height of a wave pool

  1. Aug 12, 2012 #1
    A 2.00 m deep swimming pool is equipped with a wave generator that sends sinusoidal waves across the pool. The equation which gives the water depth, h(x,t), some distance x from the wave generator at any time t is:
    h(x,t) = 2.00 m + H cos[ 2π [ t/(4.900 s) − x/(0.4000 m) ] − 5π/4 ]
    where H = 75.0 cm.

    a. What is the change in water height, with respect to the mean water level, a distance 34.81 m from the wave generator at time t = 10.50 s.

    b. How much time must elapse from the instant in part (a) until the water 34.81 m from the wave generator reaches its next maximum?


    For a, have been trying to do the question and I'm using deltah = H cos[ 2π [ t/(4.900 s) − x/(0.4000 m) ] − 5π/4 ] but obviously its wrong cuz I'm getting the wrong answer.
     
  2. jcsd
  3. Aug 12, 2012 #2

    gneill

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    Staff: Mentor

    You should show details of your actual calculation attempt so that we can see what's going wrong (and it's possible that the "book" answer is incorrect -- it happens sometimes).
     
  4. Aug 12, 2012 #3
    Oh, never mind. I was doing the right thing but I didn't know you had to set your calculator to radians. Thanks, anyway.
    Hmm, but I still don't know how to do the next bit. Do I have to use the equation again? It doesn't look like I can...
     
    Last edited: Aug 12, 2012
  5. Aug 12, 2012 #4

    gneill

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    Ah. That'll do it, all right.

    Cheers.
     
  6. Aug 14, 2012 #5

    Redbelly98

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    Actually yes, you do use that same equation. What is the value of Δh at a maximum?

    p.s. Welcome to Physics Forums.
     
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