When air is heated, it expands as its molecules spread out away from each other. In other words, hot air is less dense than cool air. This means that hot air will rise above cool air, and that's exactly what you're seeing with this spinning snake! As the hot air rises up, cooler air flows in to replace it - but then the cool air gets heated by the candle, and the whole thing repeats. This cycle of moving air is called a convection current.
Convection currents are all around us. They cause wind, all kinds of weather, and affect ocean temperature. They're even in our ovens! Download the printable here to create a mesmerizing, moving sculpture using convection currents!
Cut a long piece of thread. The thread should be able to touch the floor from the top of the chairs. Then, thread the needle.
Stick the needle through the dot in the center of the snake’s body.
Tie a knot on the underside of the snake.
Place the chairs about 2 feet (.6 meters) apart. Then, balance the cardboard tube in between them.
Tie the end of the thread to the broom so that the snake hangs about 1 foot above the floor.
Place the candle directly underneath the snake.
Light the candle!
The rising hot air makes the snake spin because of the shape of the spiral. Just like in a pinwheel, the air gives the snake a push in one direction and starts it spinning. In a frictionless world, the snake would keep spinning forever (or, at least until the candle burned out). Our snake is attached to a thread, so it’ll stop once the thread twists up can can’t spin any more. If this happens, just untwist the string and try it again - your snake will start spinning again!
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