Newtonian Water-Rocket Hydro-Propulsion Lab

60 mins Ages 7-9 Outdoor

An engaging, screen-free learning activity that builds real-world creativity and critical thinking for kids aged 7 to 9.

Materials Needed

  • • 2-liter plastic soda bottle (carbonated beverage type) (1 unit)
  • • Rubber or tapered natural cork stopper (1 unit)
  • • Bicycle floor pump with inflation needle (1 unit)
  • • Corrugated plastic or stiff cardboard for fins (3 cut pieces)
  • • Duct tape (1 roll)
  • • Water (1 liter)

Pro Tips

  • → The optimal water volume is approximately one-third of the bottle capacity; water provides reaction mass while compressed air provides the energy spring.
  • → Tape three cardboard stabilizer fins to the base so the rocket’s center of pressure sits behind its center of gravity.
  • → Ensure the needle passes through the cork securely without leaking air before final pressurization.

Safety First

Conduct launches strictly in a wide open field. Never lean over a pressurized bottle.

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Step-by-Step Instructions

1

Step 1

Cut and tape three triangular cardboard fins symmetrically around the neck of an empty 2-liter bottle.

2

Step 2

Push a bicycle pump needle valve through the center of a rubber or tapered cork stopper.

3

Step 3

Fill the bottle one-third full with water, insert the cork firmly into the nozzle, and mount the rocket on an outdoor launch stand.

4

Step 4

Stand back and pump air into the bottle until hydraulic pressure ejects the cork, propelling the rocket into the air.

What they are learning

Newton’s Third Law of Motion (action/reaction) Pneumatic compression and fluid momentum Aerodynamic center of pressure stability