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Homework Help: How Do I Know the Following Equations is Dimensionally Correct?

  1. Jan 19, 2010 #1
    1. The problem statement, all variables and given/known data
    The problem asks to choose the dimensionally correct equation. In the back of the book it says that the correct answer is y=2 cm * cos(k*x), where k=2 m^-1. What do x and y stand for? The book doesn't say. Does each variable usually represent a certain dimension in physics? From my understanding, dimension y should be the same as dimension ( 2 cm * cos(k*x) ). But what is y?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jan 19, 2010 #2


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    If you had y=cosθ, cosθ is dimensionless but θ would be in radians. What should x be then?
  4. Jan 19, 2010 #3


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    Appears to be dealing with harmonics. Notably spring harmonics. If so 'y' would be vertical or horizontal displacement.
  5. Jan 19, 2010 #4
    an angle? arc length?
  6. Jan 19, 2010 #5


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    kx should give radians if k is m-1, x would be?
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