Here is another experiment to satisfy that lurking (or obvious) scientist inside of you. Today: Can you stab a balloon without it popping?

Previous Experiments:

Fire a Rocket!

Make a volcano!

What you will need:

– Balloons!
– Metal skewer
– Vaseline
– Sharp pin
– Cello tape

What you need to do:

– Blow up a balloon – not too much – and tie the end shut
– Dip the tip of the skewer into the Vaseline and spread it along the length of the skewer
– Carefully, twisting, push the skewer into the balloon at the end opposite the knot
– Continue pushing and twisting the skewer until the tip emerges from the other end, near the knot
Ta da! A balloon kebab (not as tasty as traditional kebab though)

Now experiment…

– Try and stick the skewer into the side of the balloon
– Do you need to twist when putting in the skewer?
– How much Vaseline do you need? Do you need any at all?

The science behind the experiment:

The rubber in the balloon is made up of many long molecules linked together. These long molecules are known as polymers. These polymers are attached together by bonds chemical bonds, which is known as cross-linking. The links that hold the polymers together allow them to stretch, up to a point. When the force or tension is too great, the links holding the polymers break.
At the end of the balloon, the force pulling on the rubber is less, allowing the skewer to break some of the cross-links, but not all of them, allowing the balloon to not pop. The Vaseline simply allows the skewer to enter the balloon more easily.