Balloon in a syringe prank
Challenge your friend to inflate a balloon inside a syringe!
Warning! Only under adult supervision.
Place a barely-inflated balloon inside a syringe. If you simply move the plunger, nothing happens. Plug the nozzle of the syringe with your finger and begin to pull the piston – the balloon inflates!
By covering the syringe’s nozzle, you create a closed system with a fixed amount of air inside. When you pull out the plunger, you increase the syringe’s internal volume, which leads to a decrease in pressure in the syringe and on the surface of the balloon. The pressure inside the balloon is equal to atmospheric pressure, so the balloon inflates until the increase in volume and elastic force compensate for the pressure difference.
Impress your friends with cool experiments from the MEL Physics subscription!