Question

Question 2: (a) Write down the equation for the work done by an expanding gas and sketch this on a p-v diagram for a typical reversible process. [3 marks) (b) Starting from the first law of thermodynamics and the ideal gas law, show that for an isothermal expansion or compression of a gas, the process can be described by pv = constant. [5 marks] (c) Knowing that pv = constant for an isothermal process, derive the following equation for the work done by that process: W = RT In [6 marks] (d) 5kg of atr is compressed isothermally and reversibly from 0.084m' and 30°C to 0.006 m?. Calculate the work input and heat supplied. Assume that air is a perfect gas with R to be 287 J/kg K (6 marks]

Answer 1

Answer'- . Given that cas the work done by an expanding das pand curve . W1.2= area under the - Sodo follows the equation (b) The ideal gas which ProMRT Here, me mass of the gas R = characteristic gas constant T= abosolute Tempenature MRT are constant pr= constant

(6) W, 2=5 pdo s constant du e constant. In (42) . = MRT . In 12 h pro constant = MRT PVEP2 V2 - MRT T = Ti = Tz for isothermal process ", -2 = MRT in P .. W 12= RT Info id).W 12. = 5 (281) (38 4273) en (o =1435303) en 10.07142) 3.434,805 (~216391) 1 W, 2 =-1127527.50 J.