A single-start square-thread power screw has an input power of 3 hp at a speed of 2 rev/s. The screw has a major diameter of 2-in and a four threads per inch. The friction coefficients are 0.14 for the threads and 0.09 for the collar, with a mean collar diameter of 3-in.
(a) Find the maximum load that the screw can lift. (Express your answer to the nearest lb).
(b) Also calculate the efficiency of the screw.

Line joining liquid phase with liquid and solid phase mixture is known as: a) liquidus b) solidus c) tie line d) none of the mentioned

Fluids at rest possess no flow energy. 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?