Introduction: Upside Down Water Cup

An Air Pressure Demonstration

Step 1: Materials

Find a piece of construction paper and a flat lidded cup with water in it.

Step 2:

Place paper on top of lid of the cup.

Step 3:

Apply pressure to the paper on top of the cup. Flip upside down and release your hold on the paper.

Step 4: Explanation

Air pressure is the force exerted by air. In this experiment since the air pressure is greater outside of the cup than inside the cup the outer air pressure keeps the cardboard in place. The higher pressure outside acts on the lower pressure inside the cup.


seamster (author)2015-03-18

Nicely done! This also makes for a pretty silly but harmless prank when you're done eating at a restaurant...