## What is a "Bottle Rocket"?

A "bottle rocket" is a rocket
made from a 2 liter soda bottle (shown right). To launch the rocket,
pour some water into the bottle. Then the bottle is pressurized
using a special latch that keeps the water and air under pressure.
When the latch is released, the air pressure pushes the water out,
forcing the rocket into the air. If you use the right combination
of water and air under pressure, your rocket can travel 60 - 80
m. Bottle rockets should be built and launched with the supervision
of a qualified adult.

## What forces act on the rocket?

Several things happen once the rocket is launched. Move your
mouse over the drawing below to see them.

- The air pressure in the rocket pushes the water out
- As the water leaves the bottle, the air expands and the pressure
drops
- The force of the water pushes the rocket forward
- Air drag slows the rocket

## Experiments

- Find a 2 liter soda bottle and weigh it empty to find the
weight of the rocket.
- Find the amount of water that makes the rocket go the longest
distance. Use the simulator.
Set the pressure to 1500 kPa, the mass to 0.2 kg. Set the launch
angle to 45 degrees.
** Be sure to put a check in the "include
air resistance box.** Try 0.2, 0.5 and 1.5 kg of water. The
module draws the path of the rocket when the flight is over.
What shape does the flight path take? Why?
- How important is air resistance? Use the
mass of water
that gave you the longest distance in problem 2 only this time
remove the check mark in the "include air resistance"
box. How much farther does the rocket travel.
- What is the angle that makes the rocket fly the farthest?
The answer may surprise you. Use the mass of water that gave
you the best distance in problem 2. Try 40, 45 and 50 degrees.
Which angle gave the greatest range. What does this tell you
about the importance of air resistance?