Air is enclosed in a rigid cylinder containing a piston. A pressure gauge attached to the cylinder gives an initial reading of 20 psig. Determine the reading of the gauge after the piston has compressed the air to one third of its initial volume. Assume that the compression process is isothermal (i.e. constant temperature) and that the local atmospheric pressure is 14.7 psia. An aircraft carries an oxygen cylinder to which a gauge is attached. The gauge reads 100 kPa(g). The air inside the aircraft is pressurized to 8 psi above the ambient pressure outside the aircraft, which is flying at 12,000 m in a standard atmosphere (see data sheets at back). What is the absolute pressure of the cabin air and of the oxygen in the tank?