There is a membrane made of an isotropic material whose elastic modulus and poisson’s ratio are e and ν, respectively. when this membrane is elongated along x-direction with no lateral deformation in y-direction, the apparent elastic modulus (e’) determined by measured values of stress and strain in x-direction (σx and εx) should be greater than the material’s own modulus (e) due to poisson’s effect. determine the difference between e’ and e.

Abrake has a normal braking torque of 2.8 kip in and heat-dissipating cast-iron surfaces whose mass is 40 lbm. suppose a load is brought to rest in 8.0 s from an initial angular speed of 1600 rev/min using the normal braking torque; estimate the temperature rise of the heat dissipating surfaces.

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.

The sum of the normal stresses does not change as the stress state rotates through an angle. a)-trune b)- false