In: Mechanical Engineering
Indicate whether the following statements are true or false. Explain.
1. The energy of simple compressible systems can be changed by energy transfer and by work associated with volume change. TRUE
EXPLANATION: For simple compressible system volume chnage can take place which means work is associated with change and also energy transfer can take place in form of heat
2. A polytropic process with n ≠ k is adiabatic. FALSE
EXPLANATION: A polytropic process with n = k is adiabatic.
3. When an ideal gas undergoes a polytropic process with n = 1, the gas temperature remains constant. TRUE
EXPLANATION: When n-= 1 means PV = constant i.e isothermal process which is constant temperature process
4. The tires of airplanes and race cars inflated with oxygen instead of air. FALSE
EXPLANATION: Aircraft tires are filled with nitrogen because nitrogen gas is mostly inert, meaning that it requires more energy to react with other substances. This is important because at elevated temperatures, oxygen can react with rubber.
5.Given temperature and specific volume of a two-phase liquid–vapor mixture, you cannot determine the specific internal energy. TRUE
EXPLANATION: If tempearture is known then with help of steam table we can find Quality(x) using specific volume and formula V = Vf + x(Vg-Vf) and then with help of "x" using formula U = Uf + x(Ug - Uf) we can find specific internal energy
6. The properties of velocity and elevation are included in the specification of an intensive thermodynamic state. FALSE
EXPLANATION:The properties of velocity and elevation are not included in the specification of an intensive thermodynamic state because their values depends on arbitary datum choices such as zero values at the surface of the earth. For state principle these properties are not required