Tuesday, 19 June 2007

How high?

A little mathematical nonsense to see me past tomorrow's exam.

The Earth, lovely thing that it is, is 24,880 miles (40,041km) in circumference.

That's 131,369,652 feet.

Now, imagine a ribbon going right around the earth, fitting neatly to the surface. (Yes, I know all about the mountains, valleys, trees and stuff. Just imagine it for the moment and forget the lumpy bits.). So this ribbon is 131,369,652 feet long.

Now, lets cut the ribbon and put in one more foot of ribbon and then go around and make sure the new ribbon is evenly adjusted around the globe. 131,369,653 feet of ribbon.

How far away from the surface will this ribbon be?

Can you see light between the ground and the ribbon?
Can you slip a piece of paper between them?
How about a cockroach passing through the gap? A mouse? A cat? A goat?

Answer tomorrow in the comments section.


  1. Well....if it takes your mind off the exam, Lee!

  2. 3.8 inches apart
    you can see light
    you can slip a piece of paper through
    A cockroach and mouse can fit through the gap, maybe a kitten, but not a goat

  3. All the best for today, Lee. :)

  4. I am so glad I dont do maths. I can just ignore this, & wait for the answer.
    What colour is the ribbon?

  5. Wait! I need to revise my answer! 1.9 inches- forgot to divide the diameter by 2.

    So, I'll say no to the cat and goat. Yes to light, paper, roach, and mouse.

  6. Oh, was this a rhetorical question?

  7. Well done Courtney. I was all set to award half points and you came good with the 2x factor.

  8. Taking then value of Pi as 3.142, I get a gap of appx 0.32 feet, so I'd get my fist through.

  9. Oops - make that half a fist, I forgot that C = 2 Pi D, didn't I?

  10. Ah! Only half points, Peter. The difference in diameter is 0.32 feet but the difference in radius is only 0.16ft. = 1.9inches.

    I'll pay the mouse or less.

  11. Oh, just just got there! I'll pay half a fist!

  12. I'm with meggie on this.
    What colour was the ribbon?

  13. Err..how's the exam? Can I choose blue ribbon?

  14. No idea even how to start working this sum out! sorryyyyy....

  15. Thanks Lee.

    I regularly got bollocked by the Maths teacher for sitting a the back of his classes, talking about motorbikes with a fellow maths phobe. It was in the days when no-one objected to a teacher throwing an accurate wooden blackboard eraser at a kid's head.

    I was much happier later at Art college, even though root two came into photography a lot, but I was cool about that.

  16. i actually meant to post on your most recent blog about the wee little apples, but couldn't log on there for some reason. Mostly what i was moved by was the color of the wine. Most incredible Lee. Amber, glowing, transportive, fantastic. Thank you.


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