How come a balloon doesn explode when you poke a hole with sticky tape on top?
When you poke a hole in the balloon while it is inflated, you are really tearing it. The fact that the balloon is stretched out causes this tear to propagate rapidly, relieving the stress on the material of the balloon causing it to explode. However, when you place a piece of tape on the balloon and then poke the hole through the tape, the tape prevents the tear from propagating. So, the balloon does not explode.
