Solved question paper for EME Dec-2012 (B-TECH 1st-2nd)
Solved Question Paper
Elements of mechanical engineering Dec-2012
PTU • B-TECH • Mechanical Engineering • 1st-2nd • Dec-2012
elements of mechanical engineering previous year question papers on BRpaper are organized for students of Punjab Technical University’s Bachelor of Technology program, 1st-2nd semester. This section makes it easier to browse subject-wise old question papers for elements of mechanical engineering, so students can review how questions are typically framed in past exams and get a sense of the exam pattern. Many students search for elements of mechanical engineering question bank while preparing for exams, and this page is built to support exactly that kind of subject-wise browsing and revision. BRpaper is not the official website of Punjab Technical University or any institution, and it does not publish official notices or academic updates.
PART-A
1. Basic Concepts of Thermodynamics (08)
Definition of thermodynamic: Need to study thermodynamics; Application areas of thermodynamic; Difference between Microscopic (or, Statistical) thermodynamics and Macroscopic(or, Classical) thermodynamics; Brief concept of continuum; Thermodynamic System : definition, types (Open, Closed and Isolated) and their examples; Thermodynamic System Boundary : definition, types and their examples; Surroundings; Control(fixed) mass and Control Volume concept and their example ; Thermodynamic State; Thermodynamic Property: definition, types citing their examples; condition for any quantity to be a property; State postulate; Thermodynamic equilibrium (which includes Thermal, Mechanical and Chemical equilibrium etc.); Thermodynamic path; Thermodynamic process: definition, concept of reversible process, quasi-static (or, quasi-equilibrium) process, irreversible process, conditions for reversibility and how these are met with, non-flow processes and flow processes, method of representation of reversible and irreversible process on property diagrams; Cyclic process; Thermodynamic Cycle: definition and its concept; Energy and its forms (microscopic and macroscopic); Physical insight to internal energy; Energy transfer across system boundary i.e. transient energies (heat and work); Difference between heat and work; Sign conventions for heat and work interactions; heat and work as path functions; Equality of Temperature and Zeroth law of Thermodynamics.
2. First Law of Thermodynamics and its applications (12)
Definition, essence and corollaries or consequences of first law of Thermodynamics; Expressions for First law of Thermodynamics for a control mass undergoing a Cycle and for process (i.e., a change in state of a control mass) ; Concept of Enthalpy and total energy and differentiation between the two - a thermodynamic property; Compressible and incompressible substances, Specific heats, Difference between Internal Energy and Enthalpy of compressible and incompressible substances; Representation of first law of thermodynamics as rate equation; Analysis of non-flow/ flow process for a control mass undergoing constant volume, constant pressure, constant temperature, adiabatic and polytropic processes; Free Expansion Process and its examples, its representation on Property diagram; Review of concepts of control volume; Expressions of first law of thermodynamics for a control volume (i.e. open system) ; Steady State Steady Flow process and its examples; First law analysis of Steady State Flow process e.g. isochoric, isobaric, isothermal, isentropic and polytropic process; Throttling process and its applications; Flow energy or inertial energy of flowing fluids or, Energy transport by mass; Application of Steady State Flow Energy Equation to various engineering devices.
3. Second Law of Thermodynamics (16)
Limitations of first law of thermodynamics; and how 2nd law is fully able to explain away and thus overcome those shortcomings of Ist law; Thermal Reservoirs, source and sink (Low temperature and high temperatures); Heat Engine, Heat Pump and Refrigerator: definitions, working, efficiency/performance and their real life examples. Justification as to why the actual efficiency of Heat Pump and Refrigerator shall also be ≤ 100% though on the face of it seems to be more than 100%; Various statements of Second Law of Thermodynamics and their equivalence; Philosophy of Carnot cycle and its consequences viz. how each of the individual four processes constituting the cycle contribute in optimizing the output and efficiency of the cycle; Carnot Engine, Carnot Refrigerator and Carnot Heat Pump: definitions, working, efficiency/performance and Limitations of the cycle; Carnot theorem for heat engines, refrigerators and heat pumps; derivation of Carnot efficiency/COP (which seems to be more than 100%); Thermodynamic Temperature Scale; Clausius theorem and Inequality; Philosophy and concept of entropy; Entropy changes during various processes; Temperature - Entropy Chart and representation of various processes on it; Principle of Increase of Entropy; Applications of Entropy Principle; Quality of Energy viz. high and low grade energies; Degradation of Energy; Third Law of Thermodynamics.
PART-B
4. Gas Power Cycles (12)
Introduction; Concept and philosophy of Air Standard Cycle alongwith associated assumptions and advantages; Air Standard Efficiency; Nomenclature of reciprocating piston-cylinder arrangement with basic definitions such as swept volume, clearance volume, compression ratio, mean effective pressure etc; Otto Cycle (or constant volume heat addition cycle), Diesel cycle (or constant pressure heat addition cycle) and Dual cycle (Mixed or Composite or Limited Pressure cycle) with their representation on P-V and T-S charts, their Air-standard (thermal) Efficiencies; Brayton Cycle, Comparison of Otto, Diesel and Dual cycle under some defined similar parametric conditions; Introduction to heat engines; Merits of I.C. Engines and their important applications, Classification and constructional features of I.C. Engines; working of two stroke and four stroke Petrol and Diesel engines and their comparison.
5. Engineering Materials (05)
Materials and Civilization, Materials and Engineering, Classification of Engineering Materials, Mechanical Properties of Materials: elasticity, plasticity, strength, ductility, brittleness, melleability, toughness, resilience, hardness, machinability, formability, weldability. Properties, Composition, and Industrial Applications of materials: metals (ferrous- cast iron, tool steels, stainless steels and non ferrous- Aluminum, brass, bronze ), polymers (natural and synthetic , thermoplastic and thermosetting), ceramics (glass, optical fibre glass, cements), composites ( fibre reinforced, metal matrix), smart materials (piezoelectric, shape memory, thermochromic, photochromic, magnetorheological), Conductors, Semiconductors and insulators, Organic and Inorganic materials. Selection of materials for engineering applications.
6. Centroid, Centre of Gravity and Moment of Inertia: (08)
Difference between centre of gravity and centroid. Determination of position of centroid of plane geometric figures of I, U, H, L, T, C, Circular and Triangular Sections. Centroid of Composite Areas. Determination of position of Centre of Gravity (CG) of regular solids viz. Right Circular Cone, Solid Hemisphere, thin Hollow Hemisphere. Area moment of inertia & mass moment of inertia, Polar moment of inertia, Parallel axes Theorem (or transfer formula), Perpendicular axes Theorem, Radius of gyration, determination of area Moment of Inertia of I, U, H, L, T, C, Circular and Triangular Sections along various axes. Mass moment of Inertia of Circular Ring, Disc, Cylinder, Sphere and Cone about their axis of symmetry and other axes.
Solved Questions
Solved-
State the conditions for a process to be reversible.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Dec 2018 State the conditions for a process to be reversible.
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Dec 2012 Explain the term reversibility as applied to a thermodynamic process.
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Dec 2009 What is reversible process? Also write conditions for reversibility.
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Dec 2005 State the condition for a process to be reversible.
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What do you understand by thermodynamic property and thermometric substance?Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Why there are two values of specific heat for a gas?Short Answer 2 Marks Dec-2012 • PTU B-TECH
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May 2016 Define specific heat. Why are there two specific heats for gases?
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Dec 2009 Why gases have two specific heats?
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Explain the term reversibility as applied to a thermodynamic process.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Dec 2018 State the conditions for a process to be reversible.
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Dec 2012 State the conditions for a process to be reversible.
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Dec 2009 What is reversible process? Also write conditions for reversibility.
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Dec 2005 State the condition for a process to be reversible.
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Comment on the statement: The entropy of the universe tends to be maximum.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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May 2016 Comment on the statement, “The entropy of the universe tends to be maximum”.
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An engine working on Otto cycle has temperatures 300 K and 600 K at the beginning and end of the compression stroke. Determine the compression ratio and air standard efficiency.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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List the various advantages of internal combustion engines over external combustion engines.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Explain the terms isotropy and homogeneity.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Define a smart material.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Define first moment of an area about an axis.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Differentiate between temperature, heat and internal energy.Short Answer 3 Marks Dec-2012 • PTU B-TECH
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May 2019 Distinguish between internal energy and enthalpy.
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May 2018 Differentiate between temperature, heat and internal energy.
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Dec 2016 Explain the difference between temperature, heat and internal energy.
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Dec 2014 Differentiate between temperature, heat and internal energy.
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May 2010 Differentiate between temperature, heat and internal energy.
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A cylinder of volume 0.1 m3 contains nitrogen gas at 1.01 bar and 20°C. If 0.5 kg of nitrogen is now pumped into cylinder, calculate the new pressure when the cylinder has returned to initial temperature. The molar mass of nitrogen is 28 kg/mol. Assume nitrogen to be perfect gas.Long Answer 5 Marks Dec-2012 • PTU B-TECH
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May 2018 A cylinder of volume 0.1 m3 contains nitrogen gas at 1.01 bar and 20°C. If 0.5 kg of nitrogen is now pumped into the cylinder, calculate the new pressure when the cylinder has returned to initial temperature. The molar mass of nitrogen is 28 kg/mol. Assume nitrogen to be perfect gas.
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Show that internal energy I is a function of temperature only.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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The following is the equation which relates internal energy u, pressure p, and volume v for several gases: U = a + bpV. Where a and b are constants. Prove that for a reversible adiabatic process, pVγ = C where γ = b+1/b.Long Answer 6 Marks Dec-2012 • PTU B-TECH
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A steady flow thermodynamic system receives fluid at a rate of 6 kg/min with an initial pressure of 2 bar, velocity 150 m/s, internal energy 800 kJ/kg and density 27 kg/m3. The fluid leaves the system with a final pressure of 8 bar, velocity 200 m/s, internal energy 800 kJ/kg and density 5 kg/m3. If fluid receives 80 kJ/kg of heat during passing through the system and rises through 60 m, determine the work done during the process.Long Answer 8 Marks Dec-2012 • PTU B-TECH
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Two Carnot engines working in series between the source and sink temperatures of 550 K and 350 K. If both engines develop equal power, determine intermediate temperature.Short Answer 4 Marks Dec-2012 • PTU B-TECH
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A cyclic heat engine operates between 800°C and 30°C. What is the least rate of heat rejection in kW net output of engine?Short Answer 4 Marks Dec-2012 • PTU B-TECH
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A gas engine working on Otto cycle has a compression ratio 7. The pressure and temperature at the start of compression is 0.98 bar and 328K, the air gas ratio is 1.2:1. If the heating value of the gas is 3850 kJ/m3 and specific heat at constant volume is 0.719 kJ/kg-K, calculate the thermal efficiency, mean effective pressure and work done per kg of the mixture.Long Answer 8 Marks Dec-2012 • PTU B-TECH
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One kg of water at 273 K is brought into contact with a heat reservoir at 363 K. When the water has reached at 363 K, find: i) Change in entropy of water, ii) Change in entropy of reservoir, iii) Change in entropy of universe.Comprehension 6 Marks Dec-2012 • PTU B-TECH
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Dec 2012 If the water is heated from 273 K to 363 K by first bringing it in contact with a reservoir at 313 K and then with a reservoir at 363 K, what will be the entropy change of the universe?
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Dec 2011 1 kg of water at 0°C is brought into contact with a heat reservoir at 100°C. When the water has reached at 100°C, find: 1) Entropy change of water, 2) Entropy change of heat reservoir, 3) Entropy change of universe.
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If the water is heated from 273 K to 363 K by first bringing it in contact with a reservoir at 313 K and then with a reservoir at 363 K, what will be the entropy change of the universe?Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Dec 2012 One kg of water at 273 K is brought into contact with a heat reservoir at 363 K. When the water has reached at 363 K, find: i) Change in entropy of water, ii) Change in entropy of reservoir, iii) Change in entropy of universe.
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Dec 2011 1 kg of water at 0°C is brought into contact with a heat reservoir at 100°C. When the water has reached at 100°C, find: 1) Entropy change of water, 2) Entropy change of heat reservoir, 3) Entropy change of universe.
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Find the mass moment of inertia of solid cone about its axis of rotation.Long Answer 6 Marks Dec-2012 • PTU B-TECH
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Determine the polar moment of inertia of a hollow circular section whose external diameter is 10 cm and thickness is 1 cm.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Give a neat sketch of the theoretical and actual pV diagrams for a four stroke Diesel engine. Describe briefly the factors which account for deviations between these plots.Long Answer 4 Marks Dec-2012 • PTU B-TECH
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May 2018 Give a neat sketch of the theoretical and actual pV diagrams for a four stroke Petrol engine. Describe briefly the factors which account for deviations between these plots.
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May 2018 Give a neat sketch of the theoretical and actual pV diagrams for a four stroke Diesel engine. Describe briefly the factors which account for deviations between these plots.
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May 2014 Discuss the difference between theoretical and actual p–V diagrams for four stroke S.I. and C.I. engines.
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Dec 2014 Give a neat sketch of the theoretical and actual pV diagrams for a four stroke petrol engine. Describe briefly the factors which account for deviations between these plots.
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May 2013 Give a neat sketch of the theoretical and actual pV diagrams for a four stroke Petrol engine. Describe briefly the factors which account for deviations between these plots.
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Dec 2012 Give a neat sketch of the theoretical and actual pV diagrams for a four stroke Petrol engine. Describe briefly the factors which account for deviations between these plots.
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Dec 2011 Discuss the difference between theoretical and actual p–V diagrams for two stroke S.I. and C.I. engines.
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What are ceramic materials? Name some of important ceramic materials. State advantages of ceramic materials.Long Answer 4 Marks Dec-2012 • PTU B-TECH
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Dec 2016 What are ceramics? Explain classification of ceramics. Also write properties and application of ceramics.
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FAQ
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Answers about this subject, solved papers, and preparation.
01 Where can I find elements of mechanical engineering previous year question papers for Bachelor of Technology, 1st-2nd semester?
This page lists elements of mechanical engineering question papers uploaded for Punjab Technical University Bachelor of Technology, 1st-2nd semester, organized for subject-wise browsing where available.
02 Are these official Punjab Technical University question papers?
BRpaper is not the official website of Punjab Technical University. These papers are shared for reference and revision purposes only and are not official university material.
03 How can previous year elements of mechanical engineering papers help in exam preparation?
Reviewing past papers can help you understand how questions are typically framed, notice commonly repeated topics, and get a sense of the exam pattern before your own exam.
04 What kind of topics does elements of mechanical engineering usually cover?
The question papers here relate to the official elements of mechanical engineering syllabus set by the university for this course and semester.
05 Does this page include a elements of mechanical engineering question bank or solved answers?
This page focuses on providing access to the previous year question papers themselves. A separate question bank or solved answers may not be available for every paper.
06 Can I find papers for other subjects in the same Bachelor of Technology?
Yes, BRpaper organizes papers by university, course, stream, and semester, so you can browse other subjects within the same Punjab Technical University Bachelor of Technology.