Consider a falling mass(m) under gravity(9.8m/s). initial velocity of the mass is 5 m/s upwards. derive expressions for the velocity and the position of the mass(m) in terms of time and initial velocity/position of the mass. a) -how long will the mass take to reach the maximum height position? b)- what would be the maximum height the mass reach relative to its initial position?

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?