Engineering thermodynamics P K Nag chapter-1 solution
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The document contains review questions and answers related to thermodynamics. It discusses key concepts like macroscopic and microscopic viewpoints, the differences between thermodynamics and heat transfer, extensive and intensive properties, equilibrium, quasi-static processes, and pressure transducers. The document defines important thermodynamic terms and concepts and distinguishes between open and closed systems, changes of state, paths, and processes.
Engineering thermodynamics P K Nag chapter-1 solution
- 1. Review questions 1.What do you understand by macroscopic & microscopic viewpoints? Ans.: - In macroscopic point of view only certain amount of matter is considered without the event occurring at molecular level. We consider effect of action of many molecules not each molecule. But in microscopic viewpoint, we consider each & every molecule. For e.g. – velocity of each molecule/atom etc. 2.Is thermodynamics a misnomer for the subject? Ans.: - Yes, because dynamics is related to time. but, in thermodynamics we do not deal with time. 3.How does the subject of thermodynamics differ from the concept of heat transfer? Ans.: - In a process thermodynamics says that the heat transfer is occurring through some process but it doesn’t deal with how and through which mode of heat transfer the heat transfer is happening. For e.g. – In I.C engine, Thermodynamics says that The chemical energy of fuel is converting to the mechanical energy and some heat loss takes place through friction but thermodynamics don’t say that through which mode heat loss takes place. 4.What is the scope of classical thermodynamics? Ans.: -A large part of thermodynamics has developed before the development of atomic theory so, everywhere we see the application of thermodynamics that is based on classical thermodynamics. 5.What is a thermodynamics system? Ans.: - A quantity of matter or a region upon which attention is focussed in the analysis of problem. 6.What is the difference between closed system & open system? Ans.: - Closed system: - Only energy can be transferred through boundary of system & surrounding. Open system: - Both mass and energy can be transferred between system & surrounding through boundary. 7.An open system defined for a fixed region and a control volume are synonymous. Explain. Ans.: - An open system is same as control volume for a fixed system because for analysing the problem we assume the open system as a fixed volume in which control surfaces are there, through which mass can be transferred.
- 2. 8.Define an isolated system? Ans.: - The system through which No mass and energy can be transferred is called an isolated system. 9. Distinguish between the terms ‘change of state’, ‘path’, and ‘process’. Ans.: - The state of thermodynamic system changes from one state to another is called ‘change of state’. The succession of states passed through during a change of state is called a path. The change of state with completely known path is called a process. 10.What is a thermodynamic cycle? Ans.: - Series of state changes such that final state is same as initial state is called a cycle. 11. What are extensive and intensive properties? Ans.: - Extensive properties are dependent on mass or mole. e.g.- mass, volume, etc. Intensive properties are not dependent on mass or mole. E.g.- density, pressure, etc. For e.g. – I have a container 1 with water and if I attach another container with container 2 with water then the volume and mass of water increases but pressure and density won’t increase. 12.What do you mean by homogeneous and heterogeneous system? Ans.: - A quantity of matter whose chemical composition & physical structure are same throughout the matter is called Homogeneous mixture. A quantity of matter whose chemical composition & physical structure both are different throughout the mixture is called heterogeneous mixture. 13.Explain what you understand by thermodynamic equilibrium. Ans.: - A system is said to be in thermodynamic equilibrium when no change in any macroscopic property.
- 3. 14. Explain mechanical, chemical & thermal equilibrium. Ans.: - 15. What is quasi static process? What is characteristics feature? Ans.: - A process in which system change its stage from thermodynamic equilibrium to another state through infinite no. of states, the path traced by all the states is called quasi static process. Quasi static process is also called reversible process means it can be performed from both state (1 2) & state (2 3) . 16.What is the concept of continuum? How will you define density & pressure using this concept? Ans.: - Consider a system, from a macroscopic point of view, we always consider that a large no’s of molecules are inside a particular volume. But from a microscopic point of view, if we consider any infinitesimal volume then it may happen that no molecules can be inside volume then we cannot define the property like volume but concept of continuum says that even though the volume is infinitesimal small we consider a large no. of molecules are inside the volume. P = F / A = mg / A = ρ v g / A We can substitute ρ from the definition of density. 17. What is vacuum? How can it be measured? Ans.: - A Region Where pressure is less than the atmospheric pressure that region is called vacuum & pressure in the region is called vacuum pressure.
- 4. For e.g. – I have a box in which air is filled and if I remove some amount of air from the box then it is called vacuum. It can be measure by (Bourdon pressure gauge, manometer etc.). 18. What is pressure transducer? Ans.: - A pressure transducer is a device which measure the pressure. It can be both mechanical & electrical. E.g. – Bourdon pressure gauge, manometer, capacitive, etc.