9. What part of a combination vehicle is referred to as the “power unit?" A. Tractor
B. Drive axle
C. Duals
D. Either A or B

An air conditioning system consist of a 5 cm diameter pipe, operating at a pressure of 200 kpa. the air initially enters the pipe at 15°c with a velocity of 20 m/s and relative humidity of 80%. if the heat supply throughout the process is 960 w, determine the relative humidity and the temperature at the outlet

An air compression refrigeration system is to have an air pressure of 100 psia in the brine tank and an allowable air temperature increase of 60°f for standard vapor compression cycle temperatures of 77 f entering the expansion cylinder and 14 f entering the compression cylinder, calculate the coefficient of performance a. 2.5 b 3.3 c. 4.0 d. 5.0

Aquick transition of the operating speed of a shaft from its critical speed will whirl amplitude. (a) increase (b) limit (c) not affect (d) zero