Refrigerant-134a at 1 mpa and 90°c is to be cooled to 1 mpa and 30°c in a condenser by air. the air enters at 100 kpa and 27°c with a volume flow rate of 660 m3/min and leaves at 95 kpa and 60°c. determine the mass flow rate of the refrigerant. the gas constant of air is 0.287 kpa·m3/kg·k. the constant pressure specific heat of air is cp = 1.005 kj/kg·°c. the enthalpies of the r-134a at the inlet and the exit states are 324.66 kj/kg and 93.58 kj/kg.

Apositive rod is placed to the left of sphere a, and the spheres are separated. which best describes the spheres? sphere a is negative and sphere b is positive because protons from sphere a are attracted to the rod and move to sphere b. sphere a is negative and sphere b is positive because electrons from sphere b are attracted to the rod and move to sphere a. sphere a is positive and sphere b is negative because electrons from the rod move to sphere b and protons then move to sphere a. sphere a is positive and sphere b is negative because protons move from sphere b to the rod and also to sphere a.

Several processes form metal ore. match each process to its description. volcanic activity weathering hydrothermal energy rocks break down as they interact with air and water. arrowright density differences and other factors cause metals to concentrate in igneous rocks. arrowright seawater heats up from contact with hot rock, and metals dissolve in it. the water rises and contacts cooler water, causing metal ores to settle on the ocean floor. arrowright

Panel bc in fig. p2.76 is semi-circular, with the 3 meter radius and horizontal straight edge through point b. compute (a) the hydrostatic force of the water on the panel, (b) its center of pressure, and (c) the moment of this force about point b. assume atmospheric pressure on the dry side of the panel