Science!, Science! For Parties

Science! For Parties- Flaming Teabags of Doom

Are we in Boston circa 1773 because let me tell you, dear reader, we are about to have a tea party! Well sort of. I’m about to teach you a cool trick you can do with a tea bag at a party! Okay, I’ll admit it, my historical reference only has a tenuous connection to what we’re going to do today. But there will be fire, so get excited. In this edition of Science! For Parties, we are going to turn an empty teabag into a flaming rocket.
First, you’ll need to gather up your supplies. Which in this case consists of exactly one tea bag, matches or a lighter, and some kind of non-flammable flat surface. EZ-PZ right.
Here’s what you’ll need to do: First, empty out the teabag until its just the actual paper teabag. Carefully remove the staple and string, open it up and dump out the contents. If there is an Englishman in the vicinity cover his eyes so he’s not overcome with horror.
Next, you’ll want to gently rub the empty bag until it forms a cylinder that can stand up on its own. Stand it on your non-flammable surface. With the match or lighter, light the top of the teabag and step away. Let the flame work its way down from the top to the bottom of the teabag.
When the flame approaches the bottom of the teabag, the remaining paper will launch itself into the air in a last bit of flaming glory. Cool huh?
Okay so now that you’ve run off and done this with a whole box full of teabags you probably want to know how it works right?
Basically, as the flame works its way down to the bottom of the teabag the air inside the cylinder is heated. And, as you remember from high school science, when the temperature of a gas increases so does its volume. Even as the air’s volume increases its mass remains the same. Thus in order for the volume to keep increasing the pressure must necessarily drop. As the hot air rises and the cool air sinks to the bottom, a convection current of air is created. Generating an upward force much like the ones birds use to gain altitude when they fly.
While that is happening the mass of the paper teabag decreases as it burns. At a certain point, the upward force generated by the convection current becomes larger than the force of gravity on the decreased mass of the teabag and the remnants of the bag shoot brilliantly upwards into the air.
Its a hell of a trick for the next time someone invites you over for a cup of tea.

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