Praxis: Make a tea bag dance like a ghost
By Medicine Hat News on October 28, 2017.
Halloween is just around the corner! This is one of my favourite times of the year to do science. There are so many spooky, eerie and fun science activities you can do. If you are having a party, you can easily turn many of the more common experiments into a Halloween theme. You could make a bubbling witches brew, dancing frankenworms, examine some pumpkin guts, or figure out how these ghosts are flying around! I am sure it will be spooktacular. Let’s get started! *Remember to ask an adult before doing this experiment. Use Caution! This activity involves the use of fire. As such, this activity should only be performed under adult supervision in a safe location such as in the safety of a fume hood or far away from buildings, furniture, trees, or other objects than can catch on fire. Materials – tea bags (Tazo work well) – glass baking dish – fire extinguisher (nearby for safety) – safety goggles – scissors – fine tipped black marker – BBQ lighter Procedure Find a safe location. Put your safety glasses on. Using the scissors cut the top off of the tea bag. Be sure you make it nice and straight. Unfold the teabag and discard the contents of the tea bag as you do not need these for this experiment. Draw a ghostly face on one side of the tea bag with the black marker. Place the tea bag, cut side down in the middle of the glass baking dish in a safe location. Using the lighter, light the top of the tea bag. Observe. Explanation Once you lit the tea bag, you should have seen it fly off just like a ghost on Halloween night! High up into the sky — this is why you need to do this in a safe location. I cannot stress this enough. In this experiment there is so much going on. You are learning about convention and air currents. When you light the top of the teabag, the cylindrical shape of the teabag heats the air up inside of the bag. These air molecules start to move around rather quickly and they begin to spread out and take up more space. As the air molecules spread out, the air inside the cylinder becomes less dense. The warm less dense air rises. As well, as the hot air rises, the cool air rushes in to take its place. This also creates a convection current. This convection current pushed on the tea bag and the bag begins to dance around! The principle displayed here is similar to how a hot air balloon works. Patty Rooks is senior scientific consultant at PRAXIS, “Connecting Science To The Community.” Contact Praxis at praxis@praxismh.ca, http://www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook. 26-25
