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Homework Help: Describing a motion

  1. Sep 15, 2011 #1
    1. The problem statement, all variables and given/known data
    Before starting the question, we need to find the displacement vector first.
    However, I get stuck here.

    I would like to ask(in the solution) how to "noted" that [itex]\hat{r}[/itex]=r[itex]\hat{e}_{\theta}[/itex]?

    Can you explain it in detail?
    2. Relevant equations

    3. The attempt at a solution

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  2. jcsd
  3. Sep 15, 2011 #2


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    There is nothing to explain. You misquoted the solution. It says [itex]\hat{r}[/itex]=r[itex]\hat{e}_{r}[/itex]. In plain English it says "Vector r is the same as scalar r times a unit vector in the direction of r." I am not sure why there is a "hat" over r instead of an arrow thus making the magnitude r =1, but it is what it is.
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