Do you want to demonstrate air pressure for your friends. Here is an easy way to do it.
For this trick you will need a balloon and some plastic cups. The exact amount of plastic cups needed depends on how well you succeed with the experiment. See the video for instructions.
This experiment depends on air pressure and its counterpart, suction. The balls “glue” to the surface of the balloon first with water tension. As the balloon is inflated the reduced curvature reduces the air pressure inside the cups. As the airpressure outside remains constant, the cups are pushed into the balloon.
This experiment is extremely easy to do. Try it out and see how many cups you can attach!