User Comments

1. 

   1/19/08

   urikalish

   

   [reply]
   1. 

      1/19/08

      GlossGreen

      It wasn't multiple choice this time. Us public school types don't do well with having to figure stuff out on our own.
2. 

   1/19/08

   Majik

   I'm going to guess 3.2 km more

   [reply]
3. 

   1/19/08

   kdawg68

   I'll take a guess....
   
   ~ 120,000 meteres of rope? That's too simplistic so it can't be right. I don't know if I ever got a question right in school that dealt with trains leaving stations. I usually just cheated off whoever was next to me.

   [reply]
4. 

   1/19/08

   GlossGreen

   I am so wrong with this but 40,000.5 km

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5. 

   1/19/08

   Unfettered

   About 6 KM of rope using rough figures
   
   I changed this twice, but I think I was right the first time.
   
   Except for now I notice you increased r by .001 km, not 1 km. damn your tricky unit conversions
   
   ... goes back to calculations
   
   And now, the answer is 5 meters of rope extra

   [reply]
6. 

   1/19/08

   GlossGreen

   I am so bad at math.

   [reply]
7. 

   1/19/08

   clioandme

   I liked the multiple choice version better, even if I did get it wrong.

   [reply]
   1. 

      1/19/08

      GlossGreen

      Can we get multiple choice now? Please?
8. 

   1/19/08

   urikalish

   How much more rope I'm going to need?
   1. 1m - 10m
   2. 10m -100m
   3. 100m - 1km
   4. 1km - 10km
   5. 10km - 100km
   6. 100km - 1,000km
   7. 1,000km - 10,000km
   
   

   [reply]
   1. 

      1/19/08

      GlossGreen

      100m-1km
   2. 

      1/19/08

      Unfettered

      1: You need roughly 5 meters of rope
   3. 

      1/19/08

      Majik

      1km - 10km
   4. 

      1/19/08

      clioandme

      Damn you Uri! I thought I had bought myself a little more time than that. Well, I'll just run along, but see if anything occurs to me. I'm too lazy to do the math after a day of teaching.
      
      For anyone else, Yuri did the math for a similar problem here:
      www.blogcatalog.com/discuss/entry/rope-around-the-world
9. 

   1/19/08

   urikalish

   OK, here goes...
   
   x = Additional rope needed
   r = Earth radius in meters
   old rope length = 2πr
   new rope length = 2π(r+1)
   
   x = 2π(r+1) - 2πr
   x = 2π(r+1 - r)
   x = 2π
   
   Additional rope needed to raise the rope 1 meter in the air all around the earth: 6.3 meters.

   [reply]
   1. 

      1/19/08

      Unfettered

      Heh. close enough. That's what I get for rounding Pi
   2. 

      1/19/08

      GlossGreen

      Well, I was a little off.
   3. 

      1/19/08

      urikalish

      @Unfettered
      Cool!
      
      @GG
      Don't feel bad, it's very counter-intuitive!
   4. 

      1/19/08

      GlossGreen

      I'll just have to study more for your next quiz.
   5. 

      1/19/08

      Unfettered

      I, of course, took the long way around and solved for r in km, then added .001 and multiplied by 2Pi. This just proves that mathematicians are smarter than physicists
   6. 

      1/19/08

      urikalish

      I'm a software engineer...
   7. 

      1/19/08

      Unfettered

      ok... software engineers who do math well are smarter than software engineers who do physics poorly
   8. 

      1/19/08

      urikalish

      I didn't remember you are a physicist... Hmmm... Can you start a thread and explain Schrödinger's cat interpretations?
   9. 

      1/19/08

      Unfettered

      ok.. physics student. By explaining SC, do you mean why the cat isn't really both alive and dead simultaneously?
   10. 

       1/19/08

       urikalish

       Maybe the popular science group is a better place for this thread...
       www.blogcatalog.com/group/popular-science
   11. 

       1/19/08

       Unfettered

       I'll consider posting something there, Uri. I'll have to read up on the Copenhagen Interpretation first, to make sure I know what I'm talking about. But yeah.. that would be the place to do it.
   12. 

       1/19/08

       urikalish

       That will be cool^2
10. 

    1/19/08

    crpitt

    So the answer wasn't a cat?

    [reply]
    1. 

       1/19/08

       GlossGreen

       That was the last one. Keep up with the times.