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!


Eric W. said...

"They were right; I was wrong!"

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

Laurie T. said...

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?

Brian said...

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

Dean Baird said...

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?)

stevieray said...

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).

Dean Baird said...

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.

stevieray said...

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