"Engineering is the closest thing to magic that exists in the world." - Elon Musk
Another engineering challenge to tackle. Balloon powered vehicles require a delicate balance of forces in order to allow the force of the balloon the successfully make the car roll. Follow these steps, but don't be afraid to tinker on your own! This version uses playing cards instead of water bottles
Materials:
Playing cards
Scissors
Straws (colorful)
Coffee Stirrers (thin straws)
Balloons
Tape
“Wheels”-plastic bottle caps, tealights/ poker chips
Procedure:
Poke holes in 4 “wheels”, the same size as the black straws
Cut a black straw in half so that it is an inch wider than a card.
Cut a colorful straw into the same width as a card. Repeat this with the same straw.
Place the cutted black straw through the cutted colorful straw.
Put wheels on each end of the black straw. Make two to form two axles for the car. (you can do so by cutting slits on the ends of the coffee stirrers and taping it onto the wheel)
Tape the two cards together, slightly overlapping, to form a base.
Tape the wheelsets to bottom of the two cards.
Put a balloon over a straw, and tape the balloon onto the straw to prevent leaking air.
Tape the balloon (motor) on top of the playing cards.
Blow into the straw. Pinch the end of the straw shut. Then let go. And you have your balloon-powered car! Congratulations! To take it a step further, continue improving your design and think of ways to have your car travel farther and for a longer time.
The Science Behind It
Have you have ever blown up a balloon and let it go, without tying it shut? The air rapidly escapes from the balloon, making it fly all over the room! This is because when you blow up a balloon, air pressure increases inside the balloon. The air pressure stretches out the elastic rubber of the balloon, like stretching a rubber band. The air pressure and stretched rubber store potential energy, or stored energy.
When the balloon is let go, the rubber shrinks and air is rapidly squeezed out through the opening of the balloon. The potential energy is converted to kinetic energy, or energy of motion of the air going out. The air is pushed out backwards, while the reaction force pushes the balloon forward. This is your car’s propulsion system! The principle at work is Newton’s Third Law of Motion, which states that for every action, there is an equal but opposite reaction.
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