What you need:
A flexible plastic bottle with a sipper/narrow mouth (table ketchup bottles and shampoo bottles work well for this)
Two straws, one narrow and one broad (the broad straw should fit loosely over the narrow straw)
Modelling clay
What to do:
1. Fit the narrow straw into the sipper mouth of the plastic bottle. Leave most of the straw’s length sticking out of the bottle.
2. Seal the mouth of the bottle around the straw using modelling clay.
3. Now, push one end of the broader straw into the modelling clay. Continue to push the whole straw out of the clay so that only a ‘plug of clay remains inside the mouth of the straw. (If you’re planning to have a battle, we suggest creating a separate larger plug to put outside this end of the straw as well, so that it does not injure anyone.)
4. Place the broader straw over the narrower one. Then, turn towards an empty space and squeeze the bottle. Alternatively, you can make another one of these and your friend can join you.
What happens:
The broader straw launches off like a rocket! The more flexible the bottle, the farther the straw flies.
Why?
Sir Isaac Newton, the famous scientist gave us three laws of motion. Of these, two laws are behind the flight of the straw.
The first law of motion states that an object at rest remains at rest, and an object in motion keeps moving until an external force acts on it. So our broad straw will rest on the narrow straw unless we apply a force that will make it move. That force acts when we squeeze the bottle.
The third law of motion states that for every action there is an equal and opposite reaction. So for the force you downwards on the bottle, the straw launches upwards. Let’s see how this happens: There is air trapped inside the bottle. When you squeeze the bottle, you squeeze the bottle, you push the air out of the thinner straw, which is the only exit point in the bottle. This air travels the length of the thinner straw and reaches the mouth of the broader straw, finds it blocked with a clay plug and pushes against it. This force causes the straw to launch off.
Picture Credit : Google
