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Ur in a room with a magnet and an iron bar how do u know which one is the magnet

  1. Mar 11, 2009 #1
    ur in a room with 2 iron bars one is a magnet and the other is not , they are the same shape
    and size , how do u tell which one is the magnet and all u have is the 2 bars to test this nothing else in the room.
     
  2. jcsd
  3. Mar 11, 2009 #2

    berkeman

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    Ooo, Ooo, I know, I know.

    Is this for homework/coursework, or a Brain Teaser? Do you have an answer you can PM me, so I can allow the thread to continue?
     
  4. Mar 11, 2009 #3
    this was asked to my physics class and i was just wondering if someone
    could tell me , cause my teacher didn't tell us yet.
     
  5. Mar 11, 2009 #4

    berkeman

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    Well, we're not going to do your classwork for you. I'll move this to the Homework Help forums, and offer you one clue... You need to figure out this homework/coursework yourself (see the "Rules" link at the top of the page).

    Hint -- what things can you do with a magnetized iron bar that you cannot do with non-magnetized iron bar?
     
  6. Mar 11, 2009 #5
    its not for homework
     
  7. Mar 11, 2009 #6

    berkeman

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    Your teacher asked you the question, and so far nobody in the class has figured it out. That makes it homework/coursework, as defined by the PF Rules.

    My hint didn't help at all?
     
  8. Mar 11, 2009 #7
    not really how would u tell which bar pulled which
     
  9. Mar 11, 2009 #8

    berkeman

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    I didn't say anything about pulling in my hint. Do you have a study group for that class, or some classmates that you can discuss it with? Give my hint to your study group/friends, to see if it sparks a good discussion where you can come up with the answer I have in mind.
     
  10. Mar 11, 2009 #9
    I know the answer, but I assume from this thread that I am not to reveal it.
     
  11. Mar 11, 2009 #10

    berkeman

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    Correct, thank you. If you can provide a not-too-obvious hint, though, that is okay. The OP (and his study partners or whatever) really need to do the work on this assignment. It looks like the professor is trying to make them think some :biggrin:
     
  12. Mar 11, 2009 #11
    k so where would i move this so some one can answer it.
     
  13. Mar 11, 2009 #12

    berkeman

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    We don't do your work for you. This is the PF, and we all (generally) abide by the Rules here, beause they're important.

    How would you benefit in the long term if we gave you the answer? In the short term, you would gain a bit in your grade, and in your standing in the class (assuming you lied about how you came up with the answer). In the long term, you would be hurt academically and professionally, because you wouldn't be developing the creative technical thinking skills that your prof is trying to engender with his/her question.

    Honestly, the hint that I gave you was a bit too obvious, and I should probably give myself an infraction for giving away a homework question answer. Bounce the hint off of your friends in the class, and turn it into a brainstorming session.

    If you rely on others to give you the answer to hard questions in your school work, then I can guarantee that you will fail my interview questions when you try to get a real job with your "hard-earned degree".

    C'mon, I practically gave the dang answer away!
     
  14. Mar 11, 2009 #13
    would u place the magnets in a T fashion
     
  15. Mar 11, 2009 #14

    berkeman

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    Not what I had in mind, but tell us why you think that might help...
     
  16. Mar 12, 2009 #15
    if u place them in T fashion and if there is an attraction the bottom one is the magnet
    and if there is no attraction the top one is the magnet because u are in between the poles, what did u have in mind.
     
  17. Mar 12, 2009 #16

    berkeman

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    Hey, that's not bad! I didn't think of that angle -- I'll remember that one.

    No, that's not what I had in mind. Bet you get extra credit if you and your study group figure out what I meant by my hint. Even more credit if you give attribution to the PF for the hint (shows academic integrity on your part).
     
  18. Mar 12, 2009 #17

    berkeman

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    BTW, the "T" solution is more elegant than mine. But when you're faced with a life-or-death McGiver situation, you do what you have to do!
     
  19. Mar 12, 2009 #18
    k i still have no clue how u would do it does it have something to do with electricity.
     
  20. Mar 12, 2009 #19

    berkeman

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    Nope. Per your problem statement, you are in the room with the two bars in your non-conducting pajamas.

    Re-post my hint here again, and brainstorm a bit.... You'll figure it out. Talk out loud...
     
  21. Mar 12, 2009 #20
    make a compass out of it
     
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