The pin-connected assembly consists of aluminum rods (1) and (2) and steel rod (3). The aluminum rods each have a diameter of 11 mm and an elastic modulus of E = 75 GPa. The steel rod has a diameter of 18 mm and an elastic modulus of E = 210 GPa. Assume a = 4.4 m, b = 1.4 m, and c = 1.2 m. What is the magnitude of load P that is necessary to displace point A 9 mm to the left?

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?