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Oranges and Earths

Discussion in 'CycleChat Cafe' started by cisamcgu, 9 Apr 2008.

  1. cisamcgu

    cisamcgu Veteran

    The circumference of the Earth is 40,008 km. So if a piece of string was wrapped around the equator (asuming the Earth is a perfect sphere), then the string would also be 40,008 km long. Now, imagine cutting this string and adding 1 metre to it's length, so the string is now 40,008 km + 1 metre. If the string was now lifted from the Eath's surface all the way round, how much would it be raised from the surface ?

    Now, take an orange, with a circumference of say, 15cm. Wrap a piece of string around it, then cut it and add a metre. How much would the string be lifted from the surface of the orange ?

    Answers on a postcard to ...... :angry:

  2. Arch

    Arch Married to Night Train

    York, UK
    Ah, I think I've heard this before. Is it the same for both and something like an inch (or a cm)?

    (not that I can be bothered to work it out and check...):angry:
  3. Arch

    Arch Married to Night Train

    York, UK
    no, hang on, that can't be right...
  4. Melvil

    Melvil Standard nerd

    4 miles for both and I claim.............................absolutely nothing whatsoever.
  5. DanBat

    DanBat New Member

    the same distance in each case (100 / 2Pi centimeters).

    Or if I am wrong maybe that explains why I dont have room for mudguards when i fit fatter tyres.
  6. OP

    cisamcgu Veteran

    It is the same for both, and it is, I think, about 16cm .. Which I find astounding... 40,000KM .. add a metre and it raises by 16cm !!!
  7. TheDoctor

    TheDoctor Man-Machine Staff Member

    It's about 6 inches . Use the formula for circumference of a circle
    Circumferance = diameter times pi

    If the circumference increases by a metre, or 39 inches, the diameter goes up by (39/3.14) inches or just over 12 inches, so the radius goes up by half of that.

    Checking on a calculator...16 cm is right.
  8. abchandler

    abchandler Senior Member

    Worcs, UK
    [pedant] Why would you need to cut it? Surely a piece of string wrapped around a circle would have two cut ends anyway? Or is this special torus string that we're using?[/pedant]:angry::biggrin:
  9. surfgurl

    surfgurl New Member

    My head just exploded
  10. alecstilleyedye

    alecstilleyedye nothing in moderation Staff Member

    i don't care :angry:
  11. Arch

    Arch Married to Night Train

    York, UK
    So I was almost right...

    Ok, so how many chain stitches do I need to cast on in DK yarn on a 4mm crochet hook, to crochet a hat for the earth?

    Tell me that, clever clogses....

    'coz I haven't got a clue...:blush:
  12. byegad

    byegad Guru

    NE England
    1 metre
  13. Landslide

    Landslide Rare Migrant

    Called to the bar

    Assuming you start at the brim, and want the brim to reach the equator…

    40,008km = 40,008,000m
    1m = 39.3700787"
    40,008,000m x 39.3700787 = 1,575,118,108.62"

    http://www.freepatterns.com/pages/tips/yarn_faq.html reckons 16 sts = 4" (therefore 4 sts = 1"), but recommends a size 5/6 hook for DK yarn.
    So (assuming you're happy to move up a hook size)…

    1,575,118,108.62" x 4 sts = cast on 6,300,472,434 sts.

    Given the hat will have a bit of stretch, I'd say you'll be safe with 6.3 billion stitches. Should keep you out of mischief for a while!
  14. abchandler

    abchandler Senior Member

    Worcs, UK
    Or, start at a pole, and you only need one
  15. Arch

    Arch Married to Night Train

    York, UK

    Thank you so much. I happen to have my crochet with me today, to do some at lunch. I will start now.

    1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11... Talk among yourselves, this may take some time...:biggrin: