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5th grade brain teaser

  1. Aug 28, 2004 #1
    A boat is docked at a shore. A ladder is hanged from top of the boat So that the last step is touching the water. The distance between steps is 20 cm and there are 4 steps in the ladder. A tide is raising the water-level 5 cm a min. How long will it take for the water to reach the top step.
     
  2. jcsd
  3. Aug 28, 2004 #2

    Gokul43201

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    Phew !! :confused: That's a real toughie !! Luckily, I'm not in the 5th grade. :wink: :biggrin:

    Otherwise, I may have complained about insufficient information !! :rolleyes:
     
  4. Aug 28, 2004 #3
    16 minutes
     
  5. Aug 28, 2004 #4

    Gokul43201

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    I guess you're not in the 5th grade either, eh ?
     
  6. Aug 29, 2004 #5
    I'd say a 5th grader was trying to get his hw question answered. Hmm, smart enough to trick you but not smart enough to do the problem.

    Ohh, and it is only 12 minutes.
     
    Last edited: Aug 29, 2004
  7. Aug 29, 2004 #6

    Gokul43201

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    That would be the correct wrong-answer !
     
    Last edited: Aug 29, 2004
  8. Aug 29, 2004 #7
    how is the boat docked? if it is far up on shore, not floating, and the tide level won't affect its position then i'd agree with the 12 minutes. however, if the boat is docked such that it is floating, then the tide won't move relative to the ladder.
     
  9. Aug 29, 2004 #8

    cronxeh

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    its a differential equation!

    i donno :D
     
  10. Aug 29, 2004 #9

    Math Is Hard

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    The answer seems obvious to me. No math needed. But then I live down the street from a Marina.

    (am I missing something?)
     
  11. Aug 29, 2004 #10
    Man I hate those
     
  12. Aug 29, 2004 #11

    Gokul43201

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    (No, you're not.)
     
  13. Aug 30, 2004 #12
    it will never reach the top step as the boat also rises with the tide.
     
  14. Aug 30, 2004 #13
    indeed. :smile:
     
  15. Aug 30, 2004 #14

    cronxeh

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    notice these two geeks used relativity for a 5th grade problem :tongue:


    i still think theres a differential equation..
     
  16. Aug 30, 2004 #15

    Gokul43201

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    Yes there is :

    dx/dt = 5 = dy/dt

    x(t=0) = 0

    y(t=0) = 60

    find t when x=y.
     
  17. Sep 3, 2004 #16
    hahaha funny
    the boat will just rise so the water never rises up the ladder all the way-- unless the boat sinks
     
  18. Jan 30, 2011 #17
    well i am in 5th grade so probably wrong, but wouldnt the ladder rise with the boat
    just a guess:biggrin:
     
  19. Jan 31, 2011 #18
    :rofl: :rofl: :rofl:
     
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