Something special about 2/3?

  • #1
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Main Question or Discussion Point

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?
 

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  • #2
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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.
 
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  • #4
A.T.
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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?
I have noticed lots of 1/2 popping up recently. There must be a nest somewhere.
 
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  • #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.
 
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A.T.
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  • #9
phinds
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Is there something more fundamental going on here?
Yes, you've fallen into the trap of numerology :smile:
 
  • #10
russ_watters
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Yes, you've fallen into the trap of numerology :smile:
Have you fallen into the trap of necroposting?

Too easy.

Thread locked.
 
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