Asharp through crack in a relatively large thick plate is 25 mm long. the plate is subjected to uniform uniaxial stress distributed along two opposite edges of the plate and acting perpendicular to the crack faces. the plate material’s mode i fracture toughness is reported to be 50 mpa-m1/2. at what stress value would you expect the crack to propagate rapidly, to complete fracture?

a. 78mpa
b. 6mpa
c.252 mpa

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

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?

Journeyman training is usually related (clo2) a)-to specific tasks b)-to cost analysis of maintenance task c)-to control process to ensure quality d)-to installation of machinery