Along with volcanos, magic milk, and a lava lamp, film canister rockets are a must do science experiment for kids of all ages.
Why make a film canister rocket?
- Film canister rockets are perfect for demonstrating Newton’s Laws of Motion. First the rocket lifts off because it is acted upon by an external force ( Newton’s First Law )caused by the buildup of gas produced inside the canister. This causes the lid to blow off, launching the film canister into the air.
- The rocket travels upward with a force that is equal and opposite to the downward force propelling the water, gas and lid (Newton’s Third Law).
- The amount of force is directly proportional to the amount of water and gas released from the canister and how fast it accelerates (Newton’s Second Law).
- They are great fun!
How to make a film canister rocket
Film canister or effervescent vitamin tabler container.
Alka seltzer or effervescent vitamin tablet
Fill your canister about a third full with water.
Drop in one tablet.
Place the lid on firmly.
Stand well back!
We managed to get three rockets from one tablet, so have some water standing by to replenish quickly before the tablet disintegrates.
Make it an investigation
The rockets are great fun just to set up and watch but you could turn the activity into a full investigation.
What happens if you add more or less water?
Does alka seltzer work better than a vitamin tablet?
Can you think of way to measure the height reached?
How many launches can you get from one tablet, by adding more water after the each launch?
What would happen if you added a weight to the canister?
Would this work with baking soda and vinegar?
Don’t forget that for your experiment to be a fair test you need to change just one condition and keep the rest constant, for example if you’re investigating whether a vitamin tablet works better than alka seltzer, you’ll need to keep the amount of water in the canisters the same, and shake each the same amount ( or not shake at all ).
Why does this happen?
When the alka seltzer or vitamin tablet reacts with the water it releases carbon dioxide ( a gas ). The carbon dioxide builds up inside the canister, increasing the air pressure so much that when the canister can take no more it pops off and shoots up into the air.
You can see in this photo where we trapped the gas in a balloon just how much gas is released, it’s no wonder the canister flies with such a bang.