A short compression specimen is composed of concrete and steel. The total coss sectional area is equal to 15000mm^2,comprised of 2,500mm^2 of steel surrounded by 12,500mm^2 of concrete. The specimen is subjected to an axial test load which produces a stress of 6N/mm^2 in concrete. Calculate ; the stress in steel and the test load referred to Esteel=210kN/mm^2, Econcrete=kN/mm^2

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?