Air is contained within a vertical piston-cylinder assembly as shown below. On its top, the 10-kg piston with a diameter of 100 mm is attached to a spring and exposed to an atmospheric pressure of 1bar. Initially, the piston head is at a position such that the spring exerts no force on it. The valve is then opened until the pressure of air is 428 kPa and the volume is 0.40 L. When the valve is further opened to let additional air in, the piston rises 2.30 cm more. Ignoring Figure Po Air friction between the piston and the cylinder wall, determine the pressure of the air within the cylinder when the piston is supply line (a) in its initial position and (b) in its final position, in atm. Note Air that the force exerted by the spring as the air expands within the cylinder varies linearly with x.

Air is contained in a vertical piston–cylinder assembly fitted with an electrical resistor. The atmosphere exerts a pressure of 101.325 kPa on the top of the piston, which has a mass of 50 kg and a face area of 0.10 m 2 . Electric current passes through the resistor, and the volume of the air slowly increases by 2 ft3 while its pressure remains constant. The mass of the air is 0.32 kg, and its specific internal energy increases by 20 Btu/lb. The air and piston are at rest initially and finally. The piston–cylinder material is a ceramic composite and thus a good insulator. Friction between the piston and cylinder wall can be ignored, and the local acceleration of gravity is g = 32.0 ft/s2 Determine the heat transfer from the resistor to the air, in Btu, for a system consisting of (a) the air alone, (b) the air and the piston. Also draw the schematic diagram. Hint: Refer to example

How much work must be input by the paddle wheel below to raise the piston 5 cm. The initial temperature is 100°F.