Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Importance of the number 5

  1. Sep 14, 2012 #1
    If you notice that there is symmetry in the numbers 0 to 10 this is a good place to start with what I want to talk about.

    I want to talk about the circle. If we need a technically correct circle one would need to see the symmetry of 0 to 10 and more correctly 0 to 5 and from this point 10 to 5 in a line.

    If 10 is our circumference of a perfect circle then we need to find our diameter. We know that there are 4 points in a circle so 2.5 is our diameter.

    C/d equal pi.

    Which would be 4 in this case. If you can guide me to where im steering wrong that would be appreciated.

    I think the question of a circle is symmetry and not a unusual number.
  2. jcsd
  3. Sep 14, 2012 #2
    Hi Jorgy86 - just a bit confused w nature of question re "importance of the number 5"?
  4. Sep 14, 2012 #3
    I have no idea what you're talking about. Please make yourself clear or this will be locked.
  5. Sep 14, 2012 #4
    I am trying to explain that there is symmetry in a circle and I'm confused as to why pi is an never ending number. What I want from this thread is an answer to why what I wrote is wrong fx.
  6. Sep 14, 2012 #5
    #4 sorry
  7. Sep 14, 2012 #6


    User Avatar
    Gold Member

    say WHAT ???

    Dude, you really need to study some math
  8. Sep 14, 2012 #7
    If 10 is where the symmetry ends would that not also be where my circle dots up?
  9. Sep 14, 2012 #8
    How do you find where the symmetry ends? We don't know what that means.

    In math there is a concept of a line of symmetry. Where basically you can draw a line through an object and the two sides of the line will be mirror images of each other.

    A circle as an infinite number of lines of symmetry.

    Also a circle has an infinite number of points, not just 4. We don't know what you are talking about there.

    Also, what does it mean for a circle to "dot up"? That phrase makes no sense.

    Can you please explain exactly what you mean?
  10. Sep 14, 2012 #9
    Sorry for my poor method of explaining things. I'll try once more and if I fail I will explain why.

    Yes you are correct that you draw a line through an object. I'm saying there are two lines. Horizontal and vertical. It makes sense to do this if you are making something.

    If symmetry happens at the number 10 is this not finite.

    What I'm trying to explain or figure out is the number sequence 0 through 10 round or not. I understand it's square if you go from 1 to 10 but I explained that you need to flip it from the number 5 to 10 to 5 to make it round.
  11. Sep 14, 2012 #10


    User Avatar
    Gold Member

    I understand every single one of the words you used in that sentence, but thrown together in that particular order, they just sound like gobbledegook.

    Look, nobody here is trying to give you a hard time, it's just that either you seem to be talking nonsense or we just can't figure out what you ARE talking about.

    Are you seriously suggesting that pi is not the ratio of circumference/diameter ? That WOULD be nonsense, so what ARE you suggesting?
  12. Sep 14, 2012 #11
    Due to an illness I have a hard time explaining my thoughts in better detail. If I had a dictionary stuck in the head I would probably do a better job.

    I'm not suggesting that pi isn't C/d.

    I guess what I'm saying is isn't the circumference 10.
    Diameter 2.5 because you can investigate the circle using 4 points or two symmetric lines.

    Maybe I got the diameter wrong trying to explain this.
    Last edited: Sep 14, 2012
  13. Sep 14, 2012 #12


    User Avatar
    Homework Helper

    These two quotes contradict themselves. If [itex]C/d = \pi[/itex] then [itex]C/2.5=\pi[/itex] (if you're trying to find the circumference of a circle with 2.5 as its diameter) so [itex]C=2.5*\pi[/itex] which does not equal 10.
  14. Sep 14, 2012 #13
    The diameter is a line segment from one point on the circle, that passes through the center of the circle and ends on the opposite side of the circle.

    The circumference is the distance around the circle.

    If you start at one point on the circle. Call it 0, and go half way around the circle, you will be at a point call it 5. Then a diameter of that circle passes through the point you call 0 and the point you call 5. However the length of that diameter is not 5, unless the circumference is is exactly 5*pi.

    It seems to me you are trying to map the points on the interval [0,10] onto a circle. Is this correct?
  15. Sep 14, 2012 #14


    User Avatar
    Science Advisor

    You start by talking about a circle and then immediately say, "one would need to see the symmetry of 0 to 10 and more correctly 0 to 5 and from this point 10 to 5 in a line."

    There are NO numbers automatically associated with a circle so this makes no sense at all. If you are thinking of some way of assigning numbers to a circle, or points on a circle, you will have to tell us what that circle is.
  16. Sep 14, 2012 #15
    Yes but if you have a circumference of 10 don't you divide this by the 4 points of two symmetric lines in your circle to get a diameter.
  17. Sep 14, 2012 #16
    Can we atleast agree that a circle is perfectly symmetric and maybe my "discovery" is look and behold 0 through 10 behave in perfect symmetry as well.
  18. Sep 14, 2012 #17
    I just want to affirm phinds' words and stress that no one is trying to give you a hard time. We are merely trying to speak in the same language.

    And you really must forgive me, for I am too dumb to understand. So please, let us try and understand each other.

    You say that a circle is perfectly symmetrical. I can agree with this, for any line that I can draw through the center of the circle cuts the circle into two identical pieces.

    I cannot, however agree to your statement that 0 through 10 behave in perfect symmetry as well. And for this I apologize. But please if you will, try and answer my questions so that I may learn.

    First, I do not know which numbers between 0 and 10 you refer to. Are you talking about just the whole numbers between 0 and 10? Such as 0, 1, 2, ...

    Or are you talking about all the numbers, rational and irrational alike?

    Secondly, as I cannot draw a line through numbers, I fail to see symmetry in the numbers 0 through 10. Can you please tell me in what way those numbers are symmetric?
  19. Sep 14, 2012 #18


    User Avatar
    Homework Helper

    Oh I think I see what you're saying now. If we have a circumference of 10, and you labelled it as 0-10 around the circle, if we get a diameter going through 0 and 5, we now have a circumference of 5 on one side of the diameter, and a circumference of 5 on the other side. If we do this again at right angles to the first diameter, we'll get a circumference of 2.5 in each of the quadrants (4 pieces to the circle).

    This is true, but the length of the diameter does not equal the length of the circumference in each of these sectors, the diameter will be equal to [itex]10/d = \pi[/itex] so [itex]d = 10/pi\approx 3.18[/itex]
  20. Sep 14, 2012 #19
    Well if you only look at the whole numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 everybody sees that 5 is the halfway mark. But what I wanted to show is that if you stop at the halfway mark and put 10, 9, 8, 7, 6 there you are basicly showing what a circle looks like. Which is symmetry in another way. What i mean is it doesnt end up being a square.
  21. Sep 14, 2012 #20


    User Avatar
    Gold Member

    Yeah, I'd have to agree with you on that. I've NEVER seen a circle that ended up being a square.

    Really, you continue to make statement that do not seem to make any sense.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook