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Waves and Sound

  1. Jan 15, 2016 #1
    1. The problem statement, all variables and given/known data
    The wavelength of a water wave is 4.4m and it's period is 1.5s.
    (a) what is the speed of the wave.
    (b) the time required for the wave to travel 100m.
    (c) the distance travelled by the wave in 1min.

    2. Relevant equations

    3. The attempt at a solution
    (a) v=λ/T
    v= 4.4m x 1.5s
    v= 6.6m/s

    Not sure how to complete questions (a) and (b).
  2. jcsd
  3. Jan 15, 2016 #2


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    Staff: Mentor

    The equation says to divide, but you multiplied.

    Use the units to check your calculations. velocity is in m/s, wavelength is in m, and the period is in units of seconds. The units have to work out, or you have made a math error (like multiplying instead of dividing)... :smile:
  4. Jan 15, 2016 #3
    Oops will fix right now.
  5. Jan 15, 2016 #4
    Okay I got 2.93m/s. What I me
    I meant to say not sure how to solve (b) and (c).
  6. Jan 15, 2016 #5


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    Staff: Mentor

    You just need the equation relating distance, speed and time. Use units to help you figure out the equation. What are the units of distance, speed and time? What equations can you write with those quantities so that the units are the same on both sides of the = sign?
  7. Jan 15, 2016 #6


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    Staff Emeritus
    Science Advisor
    Homework Helper

    If I'm walking down a road at 2 m/s, how long does it take me to walk 100 m? How far do I walk in 1 minute?
  8. Jan 15, 2016 #7
    Not sure if I did this correctly.

    (a) v=λ/T
    v= 4.4/1.5
    v= 2.93m/s

    t= 100m/2.93m/s
    t= 34.13s

    (c) d=vt
    d= (2.93m/s)(60s)
    d= 175.8m

    Did I do it correctly?
  9. Jan 15, 2016 #8


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    Staff: Mentor

    Looks good to me. See how carrying units along in the equations helps to keep things straight? :smile:
  10. Jan 15, 2016 #9
    Yess thanks for the help
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