g The function of those little black transformers that clog your power strips is to step down line voltage to run small electronic gadgets. Suppose a fax machine uses an ideal transformer with a primary voltage of 120 V and 300 primary windings. If the secondary voltage is 12 V, find A) the number of turns on the secondary. B) If the fax machine at idle draws enough current to dissipate 6 W, find the current that must flow in the primary g

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?

Determine whether or not it is possible to compress air adiabatically from k to 140 kpa and 400 k. what is the entropy change during this process?