PURPOSE: To demonstrate a mechanism which produces a constant water pressure.

DESCRIPTION: Air enters the aspirator bottle, initially almost filled with water, through a tube inserted through a sealed stopper into the water bath, while the water leaves through a nipple near the bottom of the bottle. This arrangement provides a constant water pressure head, which is equal to the height of the water column between the nipple and the bottom end of the tube. Thus the water jet will have the same range as the water level in the bottle falls from its initial level to the level of the bottom of the tube.

SUGGESTIONS: Before doing the experiment, let your students vote on whether the range of the water projectile will increase, decrease, or remain the same, as the water level drops.

REFERENCES: (PIRA unavailable.)

EQUIPMENT: Aspirator bottle with stopper and glass tube, pedestal, water, tank.

SETUP TIME: 5 min.

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