Question

Some air is pumped out of a tube which has one end immersed in water. The water in the tube rises above the tap A (Fig.). Will the water leak out if tap A is opened?

Answer 1

The pressure in the tube at the level of the A is smaller than the outside pressure. Therefore, when the is opened, the outside pressure does not allow the liquid to leak out. Air will enter the tube through the **** until the pressure inside equals the pressure outside and the liquid drops to its initial level.