The state of stress at a point in a body is defined by the stress components = =− = =− and == consider a plane that passes through the point and has unit normal vector (1/10, 3/10, 3/10) relative to the x, y, z. (a) find the stress vector components of the x, y, z axes acting on the plane. (b) find the magnitude stress vector components of the x, y, z axes acting on the plane. (c) find the magnitude of the normal stress acting on the plane. (d) find the magnitude shear stress acting on the plane.

If you were designing a bumper for a car, would you prefer it to exhibit elastic or plastic deformation? why? consider the functions of a bumper in both a minor "fender-bender" and a major collision.

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?