DIY Rockets

What to do:

Take an empty Berocca (or other multi-vitamin)  tube, and fill it about a quarter full with water. If you have one of those ancient devices called a “35mm film camera”, you can use a film canister instead (we’ve found the clear ones work best).

Now take an alka seltzer (less sticky) or multi-vitamin tablet place it on the inside of the lid. Before you launch the rockets, make sure they are well away from anything fragile. Now flip the tablets into the tube, then quickly seal the lid and place the tube upside-down on the table. Immediately take a few steps back to be out of the way at lift-off.

After a few seconds, the top of the tube will burst off the lid and launch into the air, leaving a trail of fizzy water behind it.


Why is that?

When alka seltzer or multi-vitamin tablets mix with water, they cause a chemical reaction. One of the things that you end up with from this reaction is the gas carbon dioxide (which you’d know best as the fizz in fizzy drinks).

As the reaction goes on, more and more carbon dioxide is produced, and with nowhere to go inside the sealed tube, it starts to build up lots of pressure. Eventually the pressure is enough to break the seal and the gas rushes out the bottom of the tube.

At this point, Sir Isaac Newton’s famous third law of motion comes into play – every action has an equal and opposite reaction. The gas rushing downwards to the exit pushes the tube upwards, causing it to launch into the air.


So what?

Well, we’d never have put a man on the moon without understanding the science of rockets! If that doesn’t seem very worthwhile or relevant to every day life, then we also need to understand the forces of equal and opposite reactions to make cars safer, design good trainers, and to develop protective clothing for sport.

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