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Power required to generate waves

  1. Mar 2, 2009 #1
    1.
    Determine the speed of transverse waves on
    a string under a tension of 73 N if the string
    has a length of 2.1 m and a mass of 5.9 g
    Answer= 161.1925893 m/s

    I have a problem with the second part of the question:
    Calculate the power required to generate
    these waves if they have a wavelength of 29 cm
    and an amplitude of 7.3 cm. Answer in units
    of kW.


    2. Velocity= Square Root [Tension/(mass/length)]

    Energy= 2 pi^2 mf^2 A^2
    A-amplitude
    m-mass
    f- frequency

    Power= Energy/time

    3. I found the frequency by taking the velocity/wavelength and then found the energy using the above equation. I tried to find a value for time by taking the inverse of the frequency (period) and then plugging the values into P=E/t, but was not correct
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Mar 3, 2009 #2

    Chi Meson

    User Avatar
    Science Advisor
    Homework Helper

    The "mass" of this equation refers to the mass of the medium through which the wave travels in one cycle. That is, the mass of "one wavelength" of the medium.

    Don't forget to convert distances to meters.

    And by the way, your answer for the speed is correct, but please...

    There are only two digits going into the equations, so there should only be two significant digits coming out. The answer ought to be 160 m/s, and few would complain if you put, 161 m/s, but you should NOT put in all the digits your calculator gave you!
     
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