Purpose: To show the large force that is exerted by the atmosphere on two disks.

Employs Guericke's Method for Demonstrating the Force of Atmospheric Pressure

Two plastic, 10cm-diameter hemispheres, each with a sturdy handle, make up this device. One hemisphere has a gasket seal; the other has a stopcock for attaching to a 0.8-1.2cm inner-diameter vacuum tubing. Join the hemispheres, hook them up to a vacuum pump, and evacuate them. Students will find it hard, if not impossible, to pull them apart. Open the stopcock to let air in, and the hemispheres separate easily.

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