A thin tube sealed at both ends lies horizontally with a 4 cm mercury plug in the middle and air at the same pressure P on both sides. When the tube is held at 3 0 ∘ to the vertical, the air columns a

Question

A thin tube sealed at both ends lies horizontally with a 4 cm mercury plug in the middle and air at the same pressure P on both sides. When the tube is held at 3 0 ∘ to the vertical, the air columns above and below the mercury are 47 cm and 45 cm. Find P in cm of Hg (one decimal). The temperature is constant.

TestHub · Accepted Answer

Each column was 2 47 + 45 ​ = 46 cm. The pressure difference across the plug is 4 cos 3 0 ∘ = 3.464 cm Hg. So 46 P ( 45 1 ​ − 47 1 ​ ) = 3.464 and P = 79.6 cm Hg.

Physics - Heat & Thermo Question with Solution | TestHub

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