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B How should I express this angle in words?

  1. Dec 4, 2017 #1
    ZL5dhwn.png

    Hi! The diagram above is showing a man swinging a swing (a facility you can find in playgrounds) back and forth. I'm trying to come up with a concise expression in words that describes the angle noted as theta so that I can write a clear and effective research question (theta is the independent variable in my research). How should I express this angle in words (or in English)??
     
  2. jcsd
  3. Dec 4, 2017 #2
    My attempt...
    Where theta is the displacement angle of the swing from equilibrium.
     
  4. Dec 4, 2017 #3

    FactChecker

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    With positive angles in the forward direction.
     
  5. Dec 4, 2017 #4

    Nidum

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    --- relative to the vertical . You must always provide a datum zero for any position variable in mechanics .
     
  6. Dec 4, 2017 #5
    So will it be
    "Displacement angle of swing from equilibrium relative to the vertical with positive angles in the forward direction"....?
     
  7. Dec 4, 2017 #6

    sophiecentaur

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    I would have thought that a diagram with the displacement angle and the restoring force marked would be quite good enough. It is a very standard set up and not likely to be to be misunderstood. Maths is often better than words to describe such things. No need to worry overmuch. I think.
     
  8. Dec 4, 2017 #7

    FactChecker

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    Even with full use of mathematics, a careful and precise definition of the variables and coordinate systems is a good practice.
     
  9. Dec 4, 2017 #8
    The problem is that I will get marks for my research question and it will be marked based on how clear the dependent and indenpendent variables are; it's mentioned in the criteria...
     
  10. Dec 4, 2017 #9

    FactChecker

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    Then you want a diagram and the correct word descriptions. The diagram helps very much to visualize but I have seen many diagrams that get too complicated to really be clear about each part. Therefore, clear word definitions are also nice.
     
    Last edited: Dec 5, 2017
  11. Dec 5, 2017 #10

    Delta²

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    Can't we simply call it "inclination angle" or "polar angle"???. Isn't it so if we choose a spherical coordinate system with its origin at the hinge? (and proper directions for positive orientation).
     
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