Aspecimen of a 4340 steel alloy with a plane strain fracture toughness of 54.8 mpa (50 ksi ) is exposed to a stress of 1985 mpa (287900 psi). assume that the parameter y has a value of 1.16. (a) if the largest surface crack is 0.2 mm (0.007874 in.) long, determine the critical stress .

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

Acompressor receives the shaft work to decrease the pressure of the fluid. a)- true b)- false

The drive force for diffusion is 7 fick's first law can be used to solve the non-steady state diffusion. a)-true b)-false