Response to the following problem:
A stationary vertical cylinder, closed at the top, contains a gas whose volume may be changed with the aid of a heavy, frictionless piston of weight w.
(a) How much work is done by the external force in compressing the gas by an amount dV by raising the piston a distance dy?
(b) If this device is used as part of an engine, what expression is appropriate to calculate the net work delivered to or received from the surroundings?
(c) If this device is used only to produce temperature changes of the gas, what expression for work would be appropriate?