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How far downstream has the boat moved?

  1. Feb 1, 2008 #1
    [SOLVED] How far downstream has the boat moved?

    I can't figure out the last part of this question. It's probably very simple and I'm just over looking it. The answers in part A are right. I just don't know how to get part B.

    A river flows due east at 1.80 m/s. A boat crosses the river from the south shore to the north shore by maintaining a constant velocity of 9.0 m/s due north relative to the water.

    (a) What is the velocity of the boat relative to shore?
    9.178 m/s
    78.69° (north of east)


    (b) If the river is 400 m wide, how far downstream has the boat moved by the time it reaches the north shore?
    m
     
  2. jcsd
  3. Feb 1, 2008 #2

    arildno

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    1. Find out the time the boat takes to traverse the 400 meters in the northern direction, at speed 9 m/s

    2. Then find out the boat's (eastern) dowstream displacement in the same time .
     
  4. Feb 1, 2008 #3
    So to fine the time it takes the boat to go 400 meters at a speed of 9 m/s. I divided 400/9.0 and got 44.4444s.

    Then I thought to find the downstream displacement given that time you would just divide the 44.444s/(1.8m/s)? But that's wrong and I don't know what else to do?
     
  5. Feb 2, 2008 #4

    arildno

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    What is distance?

    Velocity MULTIPLIED WITH time!
     
  6. Feb 2, 2008 #5
    SOLVED thanks...sorry for some reason I thought you divided it.
     
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