Experimental glass blowing for boys

by Carleton John Lynde

Experiment 20. Magic.

FIG. 33
THE SUBMARINE SUBMERGES

Fill a bottle to overflowing with water, insert the submarine open end down, insert the solid rubber stopper and press down hard (Fig. 33). Does the submarine submerge?

Release the stopper. Does the submarine rise and does it also move forward?

Turn the bottle on its side and release the stopper quickly. Does the submarine shoot forward at a great rate (Fig. 34)?

The submarine acts in this magical manner for the reasons given in Experiment 9. When you press the stopper in, you compress the air in the submarine and force water in until the submarine weighs more than an equal volume of water and it sinks. When you release the pressure on the stopper, the compressed air forces the water out until the submarine becomes lighter than an equal volume of water and it rises. The water rushing out through the opening exerts pressure backward on the water in the bottle and the reaction drives the submarine forward.