When we release air from the balloon , why does it move as if something is pushing it. It goes almost like a rocket launched from a launchpad (only that it does not go in well defined trajectory)? what is the physics behing this phenomenon?
asked Mar 03 '12 at 14:27
It is because of the Thrust. And it is the best example of Newton's second law and third law. Let me rephrase them if you dont remember -
Newtons second law states - "The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector."
Newtons third law states - "To every action there is an equal and opposite reaction"
When you let go air from the balloon, the air accelerates in one direction and hence causing a force in opposite force that pushes balloon in opposite direction. Another important factor working here is air pressure inside the ballon that creates the original force of the air.
The same principle is also used for launching rockets (as rightly pointed by you in the question)
answered Mar 08 '12 at 16:18