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Homework Help: Basic Vectors Problem

  1. Aug 22, 2010 #1
    Huck Finn walks North across a raft at a speed of 1.0 m/s while the raft is traveling east at a speed of 2.7 m/s relative to the river bank. What is the velocity of Huck relative to the river bank?

    Well can't really think of any

    I'm REALLY new to physics and I was stumped from the start. Apparently the answer is 2.9 m/s but I'm absolutely lost. Anyone help out a clueless fool?
  2. jcsd
  3. Aug 23, 2010 #2
    so try drawing a diagram of this. Break this up into X, and Y components (do you know what components are?) So huck is moving 1.0 m/s in the +y direction and 2.7 m/s in the +x direction due to the river. So how do we add vectors? we use the Pythagorean theorem to find the magnitude (although you don't really need to do this, you can just express your answer in terms of i and j unit vectors).

    Once you find the magnitude, you can find the angle from the axis parallel to the river bank using trig inverse functions.
  4. Aug 23, 2010 #3
  5. Aug 23, 2010 #4
    you're welcome. I presume you had no problems?
  6. Aug 27, 2010 #5
    Yeah dude, it's simple after your explanation.
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