Air contained in a rigid, insulated tank fitted with a paddle wheel, initially at 4 bar, 40oC and a volume of 0.2 m3, is stirred until its temperature is 353oC. Assuming the ideal gas model with γ=1.4 for the air. Ignore kinetic and potential energy. Determine: (a) (10%) the final pressure, in bar; (b) (15%) the work, in kJ; (c) (15%) the amount of entropy produced, in kJ/K.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

An electrical motor raises a 50kg load at a construct velencity .calculate the power of the motor, if it takes 40sec to raise the load through a height of 24m(take g =9.8n/g)

The mass flow rate of the fluid remains constant in all steady flow process. a)- true b)- false