DIY: The Invincible Bag

What do DNA, RNA, styrofoam, and Ziploc bags have in common? They’re all made of polymers! Polymers are macromolecules, or long chains of repeated small parts. They’re stretchy, tough, and omnipresent– polymers even encode your body! Individual molecules are too small to be directly observed by humans, but we can see some of the properties of polymers in action with a simple experiment.

PolymerizationIndividual molecules of nylon bond together to form a polymer.

When a sharp pencil tip pushes between the polymers, they stretch tight around its surface. This snug plastic hug keeps the water sealed inside, and the pressure of the water helps keep the seal in place. You’re not damaging the individual molecules the bag is made up of, you’re just separating them!

Invincible BagWatching this really feels like a trick, so this is definitely a great one to try it at home! All it takes is some sharp pencils, a ziploc bag, and some water.

Take the ziploc bag and fill it up most of the way with water. Make sure to leave a bit of an air bubble at the top, or the bag will leak due to extra pressure created by the pencils displacing the water. Then take the pencils and stab them through the outer wall of the bag. It feels awesome, and it looks cool too!

Screen Shot 2016-03-30 at 11.22.27 AMHow many pencils can you stab through one bag?

Written By: Scott Alton


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