(20 pts) air enters a convergent-divergent nozzle at 20 × 105 n/m2 and 40 ◦c. the receiver pressure is 2 × 105 n/m2 and the nozzle throat area is 10 cm2 . (a) what should the exit area be for the design conditions above(i. e.,to operate at third critical? ) (b) with the nozzle area fixed at the value determined in part (a) and the inlet pressure held at 20 × 105 n/m2 , what receiver pressure would cause a shock to stand at the exit? (c) what receiver pressure would place the shock at the throa

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.

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false

Shafts are machine elements that are used to a) carry axial loads b) direct shear loads c) transmit power d) rotate at constant speed e) none of the above circular and square shafts subjected to the same torque under the same circum behave a) the same way b) almost the same way