ALL ABOARD: WE’RE GATHERING STEAM
Source: science-sparks.com
Celebrate the start of summer with this exciting bottle rocket experiment that demonstrates Newton’s Third Law of Motion! Make sure to read through the directions from start to finish before you begin this activity, and make sure an adult is supervising while making and launching the bottle rocket.
Materials
- An empty plastic bottle
- Cardboard made into a cone and four fins
- A cork
- A pump with a needle adapter
- Water
Directions
- Push the needle adapter of the pump through the cork. It needs to go all the way through, so you might have to trim the cork a bit.
- Decorate the bottle with the cone and fins.
- Fill the bottle one quarter full of water and push the cork in tightly.
- Take the bottle outside and connect the pump to the needle adapter. If your rocket doesn’t stand up on its fins, you can rest it on a box, but if you made some strong, stable fins, it should stand up by itself.
- Make sure all spectators stand back. Pump air into the bottle – it will lift off with force after a few seconds.
**Please make sure an adult is around, as the rocket takes off very suddenly and forcefully. Do not approach the rocket once you have started pumping even if it looks like nothing is happening.**
Why does the water bottle rocket launch?
As you pump air into the bottle, pressure builds up inside. If you keep pumping, the force of the air pushing on the water eventually becomes strong enough to force the cork out of the bottle, allowing water to rush out in one direction, while the the bottle pushes back in the other direction. This forces the rocket upwards.
Space rockets work in a similar way to the bottle, but instead of squirting water they burn fuel to make a powerful jet of hot gas. The force of the gas downwards pushes the rocket upwards. This is a great demonstration of Newton’s Third Law.
