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Homework Help: Please help with relative motion problem

  1. Nov 4, 2004 #1
    please help with relative motion problem!!!

    I need some help with this question, i know the axis needs to be rotated but i'm not sure how to go about doing that. I also need to know how to do it using the component method.

    -two canoeists, A and B, live on opposite shores of a 300m wide river that flows east at .80m/s. A lives on the north shore and B lives on the south shore. They both set out to visit a mutual friend X who lives on the north shore at a point 200m upstream from A and 200m downstream for B. Both canoeists can propel their canoes at 2.4m/s through the water. How much time must canoeist A wait after canoeist B sets out so that they both arrive at X at the same time? Both canoeists make their respective trips by the most direct routes.

  2. jcsd
  3. Nov 5, 2004 #2

    Andrew Mason

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    Think in velocity vectors. For B to get to X he moves directly toward X at a velocity consisting the sum of two velocity vectors. You know the magnitude and direction of the current flow vector (.8 m/s east). You know the magnitude of the canoe vector (2.4 m/s). You know the direction of the resultant (from B to X). So the canoe must move with velocity such that its eastward speed / northward speed = 2/3.
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