What makes a coaster placed over the rim of a glass of water stick eve

1.	What makes a coaster placed over the rim of a glass of water stick even when you invert it?
Answer» Atmospheric pressure. Normal air pressure is about 15 pounds PER SQUARE inch. The MOUTH of a glass might be about 4 square inches, so the air is pushing up on the coaster with a force of about 60 pounds.

What makes a coaster placed over the rim of a glass of water stick even when you invert it?

Answer»

Atmospheric pressure.

Normal air pressure is about 15 pounds PER SQUARE inch.

The MOUTH of a glass might be about 4 square inches, so the air is pushing up on the coaster with a force of about 60 pounds.