Exercise 19
Calculate the voltage drop on each resistor and indicate the polarity of
the voltage drop on each resistor with the switch open, as indicated.
Next, calculate the voltage drop on each resistor and indicate the polarity
of the voltage drop on each resistor when the switch is closed.

Given:
Vb1 = 7V
Vb2 = 3V
R1 = 10K ohm
R2 = 5K ohm
R3 = 20K ohm
R4 = 15K ohm

The temperature of air decreases as it is compressed by an adiabatic compressor. a)- true b)- false

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?