Water Rocket Launches

I wanted to complete the investigations and activities for “The City Water Project” last summer. The air pump broke so my water rocket launches were delayed. Fall complied with a last really nice day.

Launching a water rocket is much easier with two people. Shooting off the rocket itself is a one person task. Timing the flight is easier with two.

water rocket
Any size plastic soda bottle will work. The big ones fly higher. They can be decorated, even have fins added. Any add ons must be very secure or they will fall off when the rocket is launched and can make the rocket fly crooked. The air needle is pushed through the rubber stopper or cork.

While teaching a science class about flight and the space program, we made and launched water rockets. The common question was how high the rocket went. This is where the stop watch comes in.

The rocket was a two liter soda bottle partially filled with water. A stopper with an air needle through it is pushed in.

water rocket launches ready
The launch pad needs to be sturdy. It holds the rocket in place pointing roughly straight up. It has room underneath for the air pump hose to fit and attach to the plug.

The rocket is placed on the launch pad. The air needle is attached to the air pump. Air is pumped into the bottle until the water rocket launches.

Learning science is a lot more fun doing things like water rocket launches. Does the amount of water affect how the rocket flies? What is the flight path like? Why is the path that shape?

If you stop and think about it, the water rocket goes up, hopefully straight up, then comes down. What pushes it up? It could be the air. It could be the water. Is it both? Why?

water rocket launches happening
Air bubbles into the bottle with every push on the air pump. It doesn’t take very many before the water rocket takes off with a sound much like a champagne cork being pulled out. Water sprays out of the bottle getting the launch pad and everything around it wet.

What brings the rocket back to earth? What keeps anything from flying off into space? Gravity. And gravity has a pull of 32 feet per second squared.

This is where timing the flight comes in. The rocket spends half its time going up and half coming down. We don’t knowhow fast it is going up. We do know how fast it’s coming down as gravity is pulling it.

after water rocket launches
I wanted a picture of the rocket taking off. I got one of the rocket after it landed. The flight took less that 3 seconds, I think. It is hard to start the stop watch when the rocket launches as it happens so fast.

The speed of gravity times half the time of the flight will yield the height the rocket reached. My rocket didn’t go very high.

Those at school went much higher. Of course one person wasn’t trying to pump the air pump with one hand and start the stop watch with the other hand, then stop it as a flight lasted only a few seconds.

My water rocket is still sitting in the launch pad in my workroom. Perhaps I will find someone next summer who wants to do some water rocket launches.

Like hands on science with puzzles and stories? Try out “The Pumpkin Project.”