Water Rocket

This demonstration shows conservation of momentum. A small plastic rocket is partially filled with water then air is pumped into it which compresses the air in the chamber. When the rocket is fired, the pressure forces the water out at high speed and the rocket flies away.

* Equipment seen in the video may vary from equipment used in ND Demonstrations. See information and images below for ND equipment and setup.

Setup:

Place the toy and water on the lab table.

Turn the rocket upside down and pour the water up to the fill line. Pull back the launcher's slider towards the piston's handle. Slip the slider onto the rocket (without tipping the rocket over) and make sure it is snug. Turn the whole assembly upright. Pump about 15 strokes of air into the piston. Point the rocket across the room (away from people and objects), and pull back the slider. The rocket will fly across the room.

Notes:

Do not point the rocket at anyone or anything!

Do not use more than 19 strokes of air.

After launch, a little water will spill out onto the carpet.

Courses Used In:

  • PHY 10111

  • PHY 10310

  • PHY 10410

  • PHY 30210

Discussion and Polling Questions:

  • Will providing more fuel give the rocket more power? What if we added more air? What if we added more water?

Equipment Needed:

  • Water Rocket Toy

  • Water