Halliday, Resnick & Walker — Fluids: Problem Problem_83

Inverted glass. Partially fill a tall drinking glass with water to a depth \(h\). Cut a square of sturdy paper so that it is somewhat wider than the opening to the glass. Place the paper over the opening (Fig. 14.37a). Spread the fingers of one hand over the paper, pressing them against the glass’s rim as widely apart as possible. Grab the glass with your other hand, inverting the glass with your hand still pressing the paper against the rim. Chances are good that you can then remove your hand from the paper without the water pouring from the glass (Fig. 14.37b). The paper bulges downward but stays against the rim. If \(h = 11.0 \text{ cm}\), what is the gauge pressure in the air that is now trapped in the glass above the water?