Atmospheric Pressure Cups

Demonstrate the Force of Air Pressure Without a Vacuum Pump

In this modern variant of a famous 17th-century experiment, students place the edges of two hemisphere cups together and squeeze them, forcing out the air between them. In a tug of war, students try to pull the cups apart-a surprisingly difficult task. Each of the 7.5cm-diameter rubber hemispheres has a two-finger tug handle and two release posts.