A hermetically sealed evacuated cylinder is connected by a thin tube with a tap to an evacuated vessel of volume V. A frictionless sliding piston is suspended in the cylinder by a spring, the equilibrium position of which is at the bottom of the cylinder. With the valve closed, such an amount of gas is introduced into the space under the piston that the piston rises to a height h (Fig. 82). At what height h1 will the piston be installed if the tap is opened? The cross-sectional area of the cylinder is S, the temperature is constant. The force exerted by the spring on the piston is proportional to the displacement of the piston.