Question

take a tumbler and fill it with water cover the mouth of the Tabla with a thick card similar to that of a postcard hold the Tumbler with one hand while keeping the card pressed to its mouth with your other hand turn the Tumbler upside down while keeping the card pressed to its mouth make sure that the Tumbler is held vertical gently remove the hand pressing the card What do you observe?Does the card get detached allowing the water to spill?With a little practice you will find that the card continues to hold water in the Tumbler even after it is not supported by your hand​

Answer 1

Answer:

WHAT TO DO:-

Once you have everything in place, fill up the glass with water right upto its brim. Carefully place the glossy side of the postcard down on the rim of the glass. Keep the palm of your hand placed on the card and turn the glass upside down.

WHAT HAPPENS:-

The card remains attached to the rim of the glass and does not allow the water to flow out.

WHY THIS HAPPENS:-

This happens because the air pressure exerted on the card from underneath is greater that the weight of the water inside the glass. This is why the card manages to hold up the water not letting it spill out.

TRY THIS:-

Use regular paper, cloth, a piece of cardboard to do this experiment. Will the water remain upside-down using these materials too?

Answer 2

Keep the palm of your hand placed on the card and turn the glass upside down. The card remains attached to the rim of the glass and does not allow the water to flow out. This happens because the air pressure exerted on the card from underneath is greater that the weight of the water inside the glass.