An ideal-gas mixture with 20 kmol of oxygen, 75 kmol of nitrogen and 5 kmol of carbon dioxide enters an adiabatic turbine at 1.4 MPa and 600 K steadily. The mixture is then expanded to a pressure of 100 kPa. If the isentropic efficiency of the turbine is 85%. Determine:

a. The actual work output of the turbine per unit mass of the mixture, in kJ/kg.
b. The specific entropy generation during the expansion process, in kJ/kg. K.

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.

Modern high speed trains do not have perpendicular expansion gaps where rails are joined end-to-end any more they are mostly welded together but what might happen if there was a spell of particularly hot weather that causes inspection of the tracks?

The process in which the system pressure remain constant is called a)-isobaric b)-isochoric c)-isolated d)-isothermal