Question

A glass is filled with water up to its brim and a thick hand card placed on top of it. Now keeping the card tightly closed and pressed with palm, the glass full of water is inverted and placed upside down. The palm is gently removed from the card. It is observed that the piece of card dose not fall off the glass though the glass is full of water and its whole weight is exerting pressure on the card. Why does it happen?

Answer 1

The card does not fall because the atmospheric pressure from underneath acts upwards and is greater than the downward pressure exerted by the weight of the water.