Summer Fun – Simple, Safe Rocket

Blast Off!

Everyone loves rockets.  My students and I never get tired of them.  Besides the fun, there is a lot of good physics learning in carbon dioxide rockets.  There are many ways to make a rocket. 

The simplest rocket I’ve ever found requires only some Alka-Seltzer tablets, an old film canister, and some water.  You just put the tablet in the film canister, pour in a bit of water, and snap the cap back on the film canister.  Then step back.  It only takes a few seconds for the pressure to build up enough for the lid to come flying off with a pop.  How high can you get a lid to fly?  Try varying the amount of water and the number of tablets.  Are more tablets always better? 

Film canisters are the perfect size for the tablets to fit in flat, but any vial with a cap will work.  These film canisters used to be everywhere and you may still have some around the house.  A store that develops film may have them or you can now buy them online.

Add some math to this by making a graph.  Try one tablet, then two, then three, and so on.  Or use fractions, but breaking tablets in half and measure by halves.  Tape a yardstick to a wall nearby so that you can better estimate the height the lid reaches by eye.  Maybe you can catch the lid at the top of its flight near the yardstick with your phone camera from a side angle.  This is a nice use of a new technology to aid in a formerly hard to measure experiment. 

Record how high the lid flew, your Y variable, for each number of tablets, your X or experimental variable on a piece of paper and then try making a coordinate or Cartesian graph.  Make multiple tries, maybe three, for each number of tablets.  What can you learn from looking at your graph?

The graph isn’t necessary to have some fun with science this summer and it may be best to just start by just exploring what happens with the film canister rocket.  After the excitement wears off a bit, you might introduce the idea of the graph.