Wednesday, September 16, 2009

Tagging the monkey worm

Upon setting up the "Monkey Hunter" demo in AP Physics 2 today, we discovered that the tree's electromagnet would no longer support the monkey. For some reason, the magnet lost its magnetism after about 10 yrs of once-per-year use. Bummer. So we hung a chain of paperclips ("worm") from the weak magnet and gave it a try. Mind you, the worm is about 1 cm wide. The monkey target is more than 10 times wider! The students demanded that we use the high speed camera to capture the result. You'll need to go full-screen to see anything.



QuickTime File - MP4 (Unannotated)

Credit to my AP Physics 2 students: they had more faith than I did that this would work. I made the mistake of hyping the demo in their schedule as "The Best Demo in Physics," and they weren't going to let a technical problem get in the way. Having dealt with cantankerous monkeys in the past, I didn't think we had a chance at hitting the skinny paperclip worm. They were right; I was wrong!

7 comments:

  1. "They were right; I was wrong!"

    I think this account has been compromised. This doesn't sound like the Dean Baird I know.

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  2. That is excellent! I know getting the monkey to behave can be tricky, I never would have thought to substitute something so small. Good shootin'. The question now is, what's up with the magnet?

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  3. Congrats to the kids! That looks even cooler than the traditional monkey demo.

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  4. I'll have to check with Pasco on that. I went all out with a very elaborate "Monkey Gun" setup--all Pasco. And it's worked well for nearly a decade. The demo launcher (their projectile launcher on steroids) is no longer even sold!

    @Eric: When I'm wrong, I'm wrong. I mark the date on the calendar and celebrate the rarity annually. So now there's this and that one time in 1974. I can take it. (P.S., what do you think Brownie Points are all about?)

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  5. stevieray10:39 PM

    I guess you won't be using THAT magnet to LEVITATE the monkey later during your Uri Geller is a Charlatan lecture series.
    I wonder if there is a corroded or loose connector somewhere limiting the current through the coil?
    Who ever heard of a hunter shooting paper clips anyway but a good "save" nonetheless ('ye of little phaith).

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  6. On the Pasco "monkey dropper," the hysteresis is such that the magnet will hold the monkey when no current is passing through. The signal from the control box (activated by a photogate beam break) sends a pulse through the dropper to neutralize (maybe even repel a bit) the attachment point. So I've lost the residual magnetism on the electromagnet.

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  7. stevieray8:56 PM

    That may be what is known in the trade as a "Gauss Encounter of the Third Kind." Just trying to be helpful.

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