Dlaczego przy gwintowaniu otworu nieprzelotowego głębokość otworu musi być większa od niż długość gwintu?

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?

Burgers vector is generally parallel to the dislocation line. a)-true b)-false

What is the correct way to measure the overall length of a boat? measure from the tip of the bow to the highest point on the gunwale. measure from the tip of the bow in a straight line to the stern of the boat. measure from the tip of the bow in a straight line to the back seat. measure from port to starboard at the boat's widest point.