Inflate the balloon and hold the neck closed with the clip. Tape a paper straw to the balloon and thread the string through it. Tie the rope to two beams, remove the clip… and the “rocket” takes off!
The air pressure in the inflated balloon is higher than that of the atmosphere, but the balloon remains at rest as long as the air pressure is distributed equally throughout it. When an “exit” appears, the air pressure sharply decreases on that side of the balloon, but continues providing pressure on the inner wall on the opposite side. This pressure difference sets the ballооn in motion, even as a jet of air steadily emerges from its “nozzle.”
Dozens of experiments you can do at home
One of the most exciting and ambitious home-chemistry educational projects