T H E   N I H    C A T A L Y S T    J A N U A R Y  – F E B R U A R Y   2007


Kids' Catalyst


You want some ketchup with your fries, and there you are pounding the end of the bottle and nothing is happening. You want some honey in your tea, and it’s a lot harder to squeeze the bottle now than it was during the summer.

What we do for food!

When you’ve finally achieved the small victory of sweetening your tea, don’t just sip away. There’s science here—specifically, there’s viscosity, which basically means how something flows.

Try putting that bottle of honey in warm water for a few minutes to change the viscosity. It will be a lot easier to pour, but once it cools again, it will return to its hard-to-squeeze state.

It’s the same for gold and rock: Heat them enough and they will flow to sometimes beautiful (and sometimes disastrous) consequences.

One wonderful exception to this is something you can demonstrate in your kitchen without too much mess (or a mess that is very easily taken care of).

Today we’re serving a marvelous mixture of cornstarch and water that I affectionately refer to as "morph." I’ve also heard "glop" and "ooze," which doesn’t quite get it for me. You could try "non-Newtonian liquid," but that’s a bit long and may make classmates either look at you funny or designate you as the homework helper. I stick with morph.

For this experiment you’ll need

1 cup of cornstarch

1/2 cup (approximately) of water

Large bowl

Thick straw (a casing from a ball-point pen works perfectly)

Plastic water bottle

Time (I played with this mixture for longer than I care to admit)

Put the cornstarch in the bowl and play with it a little while. If you squeeze the powder, it will sound like crunching snow. So now that your fingers are coated in powder, start adding water a little at a time (a tablespoon will do if you are being exact) and mixing with your hands. (Of course, you could mix with a spoon, but how much fun is that?)

You will notice immediately that this is not mixing like pancake batter and milk—it doesn’t taste like it either—but that is the consistency you want to achieve for perfect morph. You will also experience something that is not at all common in liquids: If you stir slowly, there’s no particular problem. If you stir quickly, it suddenly feels as if you are stirring sand.

Try to pick up some morph. After you finally manage to get some of it in your hands, try to shape it into a ball. Trust me, it can be done. Then hold it in the palm of your hand and watch it liquidate. . . all of your hard work morphing back to its original form! But it felt solid.

After you’ve perfected the ball, try a cube. It starts caving in before you know it, but just for a moment it felt as if you could roll for your next turn.

When you finally tire of doing this, take the thick straw and poke it into the surface of the morph. What do you think will happen?

If you go slowly, the straw will go right to the bottom of the bowl. Go quickly, and you’ll never hit it. Let your hand sink to the bottom of the bowl and then pull it out. Again, going slowly is no problem. Go quickly, and you’ll pick up the bowl with one finger!

So when you’re finally told it’s time to do "real" homework instead of playing with the stuff, don’t throw it away! Discover yet another interesting property of morph by pouring it into a plastic bottle. The morph will form ribbons on its journey from bowl to bottle.

When you’re done with the experiment, just throw away the bottle, and don’t put the mixture down the drain. (Clumps would not be good for the pipes.)

Morph changes its viscosity when you apply pressure. But not honey, which is changed by temperature. Of course you could try applying pressure to honey—it will taste better in your tea, but it won’t become morph!

Jennifer White

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