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I Something special about 2/3?

  1. Oct 27, 2016 #1
    So I noticed something about problems. I see the number 2/3 or 3/2 a lot. For example, the height masses lose contact with sphere. Ladder losing contact with wall etc. Or 3/2 for the height above a rolling cue ball to strike for it to stop etc. And I notice the number 2/5 and 5/2 a lot as well. For example, the minimum height to make around the loop de loop.

    Is there something more fundamental going on here?
     
  2. jcsd
  3. Oct 27, 2016 #2

    jedishrfu

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    I think this is a result of teachers designing problems with simple exact solutions. This is not unlike the use of 30-60-90 or 45-45-90 triangles in trig or Pythagorean triplets i.e. 3-4-5 right triangles when teaching the Pythagorean theorem.
     
  4. Oct 27, 2016 #3

    robphy

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  5. Oct 28, 2016 #4

    A.T.

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    I have noticed lots of 1/2 popping up recently. There must be a nest somewhere.
     
  6. Oct 28, 2016 #5

    vanhees71

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    The worst are factors of powers of ##2 \pi##. They tend to be missing or appear to often in formulae. In this case you can trace it to Fourier as the culprit. LOL.
     
  7. Oct 28, 2016 #6

    A.T.

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    Use τ.
     
  8. Oct 28, 2016 #7

    vanhees71

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    ##\tau##?
     
  9. Oct 28, 2016 #8
     
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