Modify the program that computes paint cost to allow the user to enter the number of doorways that do not have to be painted. assume each doorway is 14 square feet. output the number of gallons needed and the cost of the job.

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?

Afluid flows with a velocity field given by v=(x/t)i.. determine the local and convective accelerations when x=3 and t=1.

The air in an automobile tire with a volume of 0.015 m3 is at 32°c and 140 kpa gage. determine the amount of air that must be added to raise the pressure to the recommended value of 206 kpa gage. assume the atmospheric pressure to be 128 kpa and the temperature and the volume to remain constant.[r-0.287 kj/kgk]