Problem 3 [20 Points] A vertical curve has an entrance grade of 4.2% and an exit grade of - 3.2%. The PVC of the curve is located at station 65 29.94 at an elevation of 871.73-ft. A 54-in diameter concrete pipe located at station 70 12.43 has an invert elevation of 874.51-ft. The concrete pipe has a 3-in thickness wall and requires a cover of at least 5-ft. a) Determine the minimum length of a curve that satisfies this requirement. b) The station of the highest point on the curve. c) The elevation of the highest point of the curve. d) The station of PVC.

Acompressor receives the shaft work to decrease the pressure of the fluid. 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?

Consider a large isothermal enclosure that is maintained at a uniform temperature of 2000 k. calculate the emissive power of the radiation that emerges from a small aperture on the enclosure surface. what is the wavelength ? , below which 10% of the emission is concentrated? what is the wavelength ? 2 above which 10% of the emission is concentrated? determine the wavelength at which maximum spectral emissive power occurs. what is the irradiation incident on a small object placed inside the enclosure?