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Finding the angular frequency of an object

  1. Mar 8, 2017 #1
    1. The problem statement, all variables and given/known data
    An object undergoes simple harmonic motion along an x axis with a period of 0.50s and amplitude of 29mm. Its position is x = 12mm when t = 0s. Determine the value of ω in the equation of motion. Suppose that ω > 0.

    2. Relevant equations

    $$ω = \frac {2π} {T}$$

    3. The attempt at a solution

    Earlier in the problem, I found that x(t) = Asin(ωt + ∅i) (which is confirmed correct). The question is asking for the angular frequency of an object going simple harmonic motion (no damping), so I am assuming I would need to just plug the period into the formula above. Thus:

    $$ω = \frac {2π} {0.5s}.$$
    $$= 12.57 \frac {rad} {s}$$

    When I submit this answer though, it says it is incorrect. I've tried entering the solution as 4π rad/s (which it said the answer needed to be in decimal format) and 13 rad/s (which it said that the answer does not have the correct dimensions).
     
  2. jcsd
  3. Mar 8, 2017 #2

    haruspex

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    You don't say specifically, but it sounds like when you submitted 12.57rad/s it did not complain about the dimensions. If so, that suggests it is happy with the 13 as the numeric value.
    Although the radian is a unit, most authorities maintain angles do not have dimension. You could try 13s-1.
     
  4. Mar 8, 2017 #3
    Thank you! 13s-1 was the correct answer.
     
  5. Mar 8, 2017 #4

    haruspex

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