Silly Putty Eats a Magnet…Slllloooowwwwllllyyyyy

The entire universe in blog form
April 8 2013 12:08 PM

It’s Alive! ALIIIVVVEEE!

sillyputty_magnet

Science isn’t cool, you hear people say? Science is boring? Science is dorky?

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

Well, maybe that last one has some credence. But I accept it fully, especially when it shows just how wrong the other claims are. For evidence, here is time-lapse video of a glob of Silly Putty eating a magnet.

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I love stuff like this. Love love love. I wish I had thought of it myself! Scott Lawson is the genius behind this; he posts videos about math and science on YouTube. The idea is actually pretty simple. He took a piece of Silly Putty and mixed iron oxide powder into it. Iron is attracted to magnets, of course, so when he put a very strong rare-earth (boron neodymium) magnet near it, the iron in the silly putty was pulled to it (and vice-versa). Silly putty is fluid, so it basically flowed over and engulfed the magnet.

It really, really looks like a white blood cell (well, a gray one) eating an attacking virus, or an amoeba attacking a protozoan. Amazing.

And it didn’t stop when it completely covered the magnet, either. The process continued until the magnet was in the center, because it’s only then that the forces are balanced. Newton’s Second Law of Motion states that an unbalanced force on a mass will cause it to accelerate (though in this case that acceleration is itself balanced by the viscosity of the Silly Putty, leaving very slow but constant motion; it’s like terminal velocity). As long as there’s more iron on one side of the magnet than the other, it’ll move. So eventually it reached the center of mass of the putty wad and stopped.

I think my favorite part of all this is just how devilishly clever it is; elegant, simple, and effective. There are several lessons in science you can glean from this, as I point out above, and it’s also engaging and fun. And heck, the whole thing here took about 90 minutes, which means it could be set up in a classroom, and the students could easily see what's going on over the course of a single period.

Now I’m off to get some time-lapse control software for my camera and start rummaging around the house for things I can film…

Tip o’ the clown posse to Have You Seen This?! via Laughing Squid via Geekologie.