Question

A hole is made at the middle of a tall jar container and water is poured into it to the level shown. See figure below.

1. Explain why water comes out of the hole, yet the atmosphere pressure acting in the directions shown are equal in magnitude. 
2. What would be observed if the container was filled with water and the top lid closed tightly?

Answer 1

1. The sum of atmospheric pressure and pressure of the water acting downwards is more than only atmospheric pressure acting horizontally, the pressure difference pushes the water through the hole
2. No water will flow out, there will be no pressure to balance the horizontal pressure difference.