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Balloon Surprise

Your friends won’t believe this!

You will need

  • balloon
  • paper clip

What to do

Balloon with paperclip inserted

Blow up a balloon and tie the neck in a knot. Look carefully at the stretched rubber in different parts of the balloon. Which parts of the balloon are stretched more? Which parts have a darker colour?

Unfold a paper clip so that one end is straight. Do not let go of the paperclip as you do this activity – otherwise you could be in danger from a flying paperclip! Stick the straight end into the balloon near the neck or near the tip. Does the balloon burst? Remove the paperclip. What happens to the air inside the balloon? Stick the straight end through the side of the balloon. What happens?

Think about it

The colour of the balloon is darker where the balloon is least stretched – near the neck and near the tip of the balloon. Slightly stretched rubber does not pull away from a hole made in it – and the air inside the balloon will leak out quite slowly. This idea is used in self-sealing fuel tanks in racing cars and aircraft. The colour is lighter at the sides of the balloon. This is where the balloon is stretched the most. Tightly stretched rubber pulls away quickly if a hole is made in it – and the balloon bursts!

Explore more

Stick some tape on the side of an inflated balloon. Stick the straight end of a paper clip through the tape and through the tightly stretched rubber on the side of the balloon. What difference does the sticky tape make? Use different types of tape. Do some types work better than others in stopping balloons from bursting?

Can you make a balloon kebab? Blow up several balloons and thread them on a long piece of wire. Where can you stick the wire without bursting any balloon?