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Homework Help: Speed, Velocity, and Time

  1. Sep 12, 2011 #1
    1. The problem statement, all variables and given/known data
    A torpedo fired from a submerged submarine is propelled through the water with a speed of 20.00 m/s and explodes upon impact with a target 2000.0 m away. If the sound of the impact is heard 101.4 s after the torpedo was fired, what is the speed of sound in water? (torpedo is held at a constant speed by propeller)

    2. Relevant equations

    3. The attempt at a solution
    I started by reading through the question and thought, if the torpedo travels 20 m/s, and it went 2000 m, then it would be traveling the length in 100 seconds. From there i thought that since it takes 101.4 s for the sound to reach the listener, I could divide 100 by 101.4, concluding that the speed of sound was 1.014 m/s. I think i am completely wrong in how to solve this problem. Please help!
  2. jcsd
  3. Sep 12, 2011 #2


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    Staff Emeritus
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    Homework Helper

    If you divide 100 seconds by 101.4 seconds, what are the units of the quotient?

    Now, you know how far the sound travels and how long it takes to travel. Don't you think that's a better approach?
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