A frictionless piston (area = 0.1963 m2 ) of unknown mass compresses air (T=25C, = 1.18 kg/m3 ) that is in a cylinder with water (T=25C, = 1000 kg/m3 ) at its bottom. The top of the piston is open to the atmosphere that has a pressure of 100 kPa. A closed manometer containing mercury (T=25C, = 13,600 kg/m3 ) is connected to the cylinder. The gas pressure above the mercury interface in the closed section of the manometer is 70 kPa. Acceleration of gravity is 9.81 m/s2 . Using this information and that provided in the figure below calculate the mass of the piston(kg). (mp = 74.2 kg)