A cylinder with a frictionless piston of mass M and cross section S is placed vertically in an atmosphere of pressure p as shown in Fig. 3. The cylinder is then rotated 180 degrees so that the opening of the cylinder faces down. Dur- ing the operation, the temperature of the gas inside the cylinder is kept fixed, and the volume of the gas is doubled. Which of the following is correct? The acceleration due to gravity is denoted as g. 3Mg 2Mg (a) p= (b) p S (c) p= Mg

A cylinder with a frictionless piston of mass M and cross section S is placed vertically in an atmosphere of pressure p as shown in Fig. 3. The cylinder is then rotated 180 degrees so that the opening of the cylinder faces down. Dur- ing the operation, the temperature of the gas inside the cylinder is kept fixed, and the volume of the gas is doubled. Which of the following is correct? The acceleration due to gravity is denoted as g. 3Mg 2Mg (a) p= (b) p S (c) p= Mg