Quiz question

1. Senior Member
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Dec 1969
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Quiz question

You have two bars of iron. <BR>One is magnetized along its length, the other is not. <BR>Without using any other instrument (thread, filings, other magnets, etc.), find out which is which.

2. Senior Member
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Dec 1969
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break one in half and push it against itself. assuming the force of the magnet is greater than the force of gravity, it&#039;ll push away from itself :-P

3. Senior Member
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Dec 1969
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LOL

Klooj_it man of steel -- breaks iron bars!!<BR><BR>Hint you have two bars!

4. Senior Member
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Dec 1969
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so? i can break them both ;-)

well, time for bed... i&#039;ll sleep on it and have one heck of an answer for you tomorrow :)

5. Senior Member
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...would be to float one of the bars. But I presume that your "no other instrument" would prohibit that.<BR><BR>Hmm...I don&#039;t see it. Have to think on it.<BR><BR>

6. Senior Member
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ok

if one&#039;s "magnetic along its length", i&#039;m taking, since this is a logic puzzle after all, that it&#039;s not "magnetic along its girth". put one down, then put the other one perpendicular, if it attracts, the first one you put down is magnetic. if not, the other one is magnetic.

7. Senior Member
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A BIG Hint

A magnet attracts iron (the other bar) to one end or the other!

8. Senior Member
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hmm

you can place end 1 of bar 1 against end 1 of bar 2, then place end 2 of bar 1 against end 1 of bar 2. if they attract in one case, then you know bar 1 is the magnet because if it was iron, and attracted the one time, it would have to attract both times (since end 1 of bar 2 is the magnetic end).<BR><BR>if it doesn&#039;t attract either time, then bar 2 is the magnet but end 2 of bar 2 is the magnetic end.<BR><BR>if it attracts both times then you know that bar 2 is the magnet and its magnetic end is end 1. :-D

9. Senior Member
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WHAT???

Not true.<BR><BR>A magnet attracts unmagnetized iron to *both* poles. It attracts a little more intensely toward the ends than in the middle, if that&#039;s what you are referring to. But I doubt that a human being could measure the difference accurately enough to be sure which was which.<BR><BR>

10. Senior Member
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Dec 1969
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If it's a logic puzzle...

...then I guess you are right. But if it&#039;s a *physical* puzzle, then a human being will be hard pressed to be able to gauge the difference in attraction between the ends and the middle. Though the longer the bar the more the difference.<BR><BR>

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