--Now on to the FUN!!
This Week's Experiment - #123 Why fireworks go bang!
Happy 4th of July from Nashville, Tennessee. As I sit here typing this, I can hear the pop and bang of fireworks from people celebrating. We have had a great week of shows, at the American Museum of Science and Energy in Oak Ridge and at the Cumberland Science Museum in Nashville. I met lots of new friends and visited with old friends at both museums.
Listening to all of the bangs, I thought it would be fun to investigate why fireworks make so much noise. To investigate this, you will need:
a balloon something with a sharp point one of the plastic canisters that film comes in (You can also use a plastic pill vial, with a snap on cap. Don't use one of the child-resistant caps, as it won't work.) vinegar baking soda tissue paper
First, blow up the balloon. What is in the balloon? Air, right? The air in the balloon is being squeezed, making it smaller than it usually is. If we let the air out of the balloon, it will get bigger, expanding to its original size. If we let the air out slowly, it expands slowly and does not make a lot of noise. On the other hand, if we took something sharp, like a pin, and made a hole in the balloon, it would rip, letting the air get bigger very quickly. As the air expands, it pushes the air around the balloon out of the way. That air pushes on the air beside it, which pushes on the air beside it, causing a wave of pushed air to move out in all directions. When this wave of pushed air reaches your eardrum, it pushes on it, causing you to hear a loud sound. The more the air expands, the bigger the push and the louder the sound. Ok, you can pop the balloon now and hear it for yourself.
