Develop a crosstabulation for the data, with x as the row variable and y as the column variable. For x use classes of 10–29, 30–49, and so on; for y use classes of 20–39, 40–59, and so on. y Grand Total 20–39 40–59 60–79 80–99 x 10–29 30–49 50–69 70–90 Grand Total

Acompressor receives the shaft work to decrease the pressure of the fluid. a)- true b)- false

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?

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false