Puff Puff Golf
Copernicus the Clown while constructing a balloon poodle at East Maitland Golf Club for a party guests, allowed his balloon to leave his hands. It sped gracefully through the air before swerving to the floor. A model car, discarded earlier by a pass-the-parcel participant, intercepted its flight. The small vehicle was propelled several metres, gathering speed as it exited the building via the open club house door. Amazed patrons watched as it careened across the practise green and drove itself directly into the hole! Puff Puff golf was created!
Brief Description: In small groups of 3 - 5 design a light weight balloon powered car using the basic materials detailed below. Propulsion of the car is generated by deflation of the balloon alone. The car must begin at the start line and finish as close to the hole as possible.
Your resources are limited to:
- Styrofoam meat tray
- Four wheels of your choice
- Skewers
- Masking Tape
- Straws
- String
- Balloon pump
Newton's Third Law of Motion
The third law of motion states that if a body exerts a force on a second body, the second body exerts a force that is equal in magnitude and opposite in direction to the first force.
“So for every action there is an equal but opposite reaction”
When holding an inflated balloon and you let go of the end, air will rush out, the action is in the direction in which it is facing as in the diagram down. The reaction will always be in the opposite direction.
This is the same principle as a rocket leaving the earth’s atmosphere. As the gases are released from the solid fuel rocket an equal but opposite force is exerted.
Again the same principle is observed when you water the garden with your hose. If you let go of the hose it will be forced backwards due to Newtons Third Law of motion.
How does a balloon propel a car?
The answer has to do with Boyle’s Law.
Boyle’s Law:
Boyle's law was named after chemist and physicist Robert Boyle, who published the original law in 1662. The law itself can be stated as follows:
For a fixed amount of an ideal gas kept at a fixed temperature, P [pressure] and V [volume] are inversely proportional (while one doubles, the other halves).
The air pressure inside of an inflated balloon is more than the atmospheric pressure outside the balloon. Also, the density inside the balloon is greater than the density outside. The molecules inside the balloon move around and bang against the inner walls. Their impacts on the inner walls produce a force, which provides the pressure of the enclosed air. Because of Boyle's Law if you squeeze a balloon to halve its volume you end up increasing the pressure on the balloon. Also pressure is directly proportional to density. That means, if the pressure in the balloon increases, so does the density, and if the pressure goes down then the density decreases also. Because of that, when you squeeze the balloon and halve its volume you increase the density of the balloon. The increase in pressure that occurs when you halve the volume of the balloon is why balloons pop when you squeeze them.