It’s easy to turn a juice bottle into a rocket launcher. How? Grab a few straws, some modeling clay, and an empty juice bottle to make a launcher that will send the straw rocket soaring across the room. Okay, you’ll learn something about Newton’s Laws of Motion at the same time.
Drink the juice! Enjoy it and then clean and dry the bottle.
Push the smaller straw into the opening of the bottle. The straw should fit snugly in the hole at the top of the bottle. Leave as much straw as possible sticking out of the bottle to hold up the larger straw.
Use modeling clay to seal any possible leaks between the straw and the hole in the bottle. The clay will also make the straw more stable and less likely to wobble.
Push one end of the bigger straw into another piece of modeling clay. This “plug” will seal the end of the straw. Cover the plugged end with something soft, like a Styrofoam packing peanut, to keep the straw rocket from hurting anyone in case they get hit (“accidentally,” of course).
It’s time to launch. Place the larger straw over the smaller straw. Ready, aim, squeeze! The larger straw launches off the smaller straw and the room erupts in a chorus of ooohs and ahhhs!
While you’re having fun launching straws, you’re actually learning about Newton’s Laws of Motion. According to the First Law, an object at rest (the larger straw) wants to stay at rest if it’s not moving and to keep moving in a straight line if it is moving. That straw will not move unless some force is applied to it to make it move. That’s where your actions come into the equation by squeezing the juice bottle. Newton’s Third Law says that for every action there is an equal and opposite reaction. As you squeeze the bottle, air is forced out of the smaller straw and pushes against the clay plug in the larger straw. The resulting force causes the straw to “launch” through the air.
Our good friend and science teacher Bruce Yeany explains it this way…
When you give that bottle a good ol’ squeeze, you’re actually shrinking its interior space. Think of it like a mini dance floor where air particles are groovin’. Squeeze the bottle, and you’re telling those air particles to get cozy—real cozy. This makes the pressure inside the bottle skyrocket. Go ahead, try it with an empty soda bottle and its cap on. Squeeze away! You’ll notice it doesn’t give much, right? That’s the pressure building up, my friends.
Now, let’s add a twist—a straw. When you put a straw into the mix, you’re basically giving the air an escape route, like a VIP exit from a crowded concert. No more pressure build-up.
Ready for some action? Squeeze that bottle fast, and whoosh. The air zooms out of the straw, propelling it forward. It’s the same science that sends a straw wrapper flying when you blow on it.
Two things will make your straw go the distance:
So, go ahead, experiment and let those straws fly.
Remember… never point the straw rocket at anyone. The goal here is to launch the rocket up in the air (not at someone). Be sure to cover the plugged end of the straw with something soft and round to protect someone from accidentally getting hurt by a sharp edge. Be creative! Once you’ve mastered the simple straw rocket, challenge your friends to a straw rocket design contest. Add a nose cone, some fins, a few decorations, and don’t forget to name your straw rocket.
This experiment was designed using the Kool-Aid® bursts juice product. While other flexible juice bottles may work, the Kool-Aid product works very well. The larger straw should fit loosely over the smaller straw. There should be no friction or resistance at all or the straw will not be able to launch. If you’re tired of searching for straws, just stop by your favorite coffee shop to pick up a few.
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