Astrain gage system is mounted on an airplane wing to measur the wing oscillations and strain during wind gusts. the system is second order, having a 90%- time of 100 ms, a ringing frequency of 1200 hz, and a damping ratio of 0.8, determine the following for this system: a)- the dynamic error when subjected to a 1-hz oscillation b)- the time lag (in seconds).

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?