A uniform tube, closed at one end, contains a 10 cm long pellet of mercury. When the tube is held vertically with its closed end pointing upward, the trapped air column has a length of 20 cm . Determine the length of the trapped air column when the tube is inverted such that the closed end faces downward. The atmospheric pressure is given as 75 cm of mercury.

Step-by-step solution

Let the atmospheric pressure be P₀ = 75 cm of Hg and the length of the mercury pellet be h = 10 cm . When the tube is held vertically with the closed end pointing upward, the open end is downward. The pressure of the trapped air is: P₁ = P₀ - h = 75 - 10 = 65 cm of Hg The initial length of the air column is L₁ = 20 cm . When the tube is inverted so that the closed end faces downward, the open end is upward. The pressure of the trapped air becomes: P₂ = P₀ + h = 75 + 10 = 85 cm of Hg Let the new length of the trappe