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Homework Help: String hanging from the ceiling

  1. Oct 19, 2012 #1
    1. The problem statement, all variables and given/known data
    A string of length L and mass m, hanging an object of mass M from the ceiling. After sending a transverse pulse from the top of the string , how much time we have to wait until the reflected pulse returned to the top?

    2. Relevant equations
    The time interval for a transverse pulse to travel the legth of the rope is ##Δt=2\sqrt{\frac{L}{mg}}(\sqrt{M+m}-\sqrt M)##.

    3. The attempt at a solution
    I think the time for waiting is just twice of Δt, but I still concern that maybe I miss something.

  2. jcsd
  3. Oct 19, 2012 #2
    Where does that equation come from?
  4. Oct 20, 2012 #3
    It is from that different points on the string have posses different wave speeds.
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