Thermodynamics
Please use these property tables attached in the additional materials section to answer these two questions:
1) An inventor proposes this method for cooling down water in an insulated bottle: fit a piston tightly against the water surface, and then pull the piston so that some of the water vaporizes and absorbs heat from the rest, which is still liquid. Calculate the work required for 100 cm3 of water initially at 20C, 1 bar, if the piston is pulled until the volume is 1 liter. Assume that the temperature is constant in this process, and the pressure outside is 1 bar.
2) I am building a compressed-air rocket starting from a one-liter soda bottle half-filled with water, the other half filled with compressed air from a bicycle pump, to which I attach a nozzle with a 2 cm2 final cross-section. When the nozzle is opened, a water jet comes out due to the air pressure, which produces thrust. Calculate the minimum initial air pressure necessary to achieve lift-off as soon as the nozzle opens, given that the instantaneous thrust is the product of the outgoing mass flow rate and the water jet velocity. Initial temperature is 20C. Neglect the weight of the bottle itself. Assume air pressure and temperature inside the bottle to be nearly constant for a few seconds
