Solved question paper for EME May-2014 (B-TECH 1st-2nd)
Solved Question Paper
Elements of mechanical engineering May-2014
PTU • B-TECH • Mechanical Engineering • 1st-2nd • May-2014
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-
If the change in energy of a closed system is known for a process between two end states, can you determine whether the energy change was due to work, heat transfer, or some combination of work and heat transfer?Short Answer 2 Marks May-2014 • PTU B-TECH
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Show how the polytropic exponent n can be evaluated if you know the end state properties (P1, V1) and (P2, V2).Short Answer 2 Marks May-2014 • PTU B-TECH
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In the absence of any friction and other irreversibilities, can a heat engine have an efficiency of 100 percent? Explain.Short Answer 2 Marks May-2014 • PTU B-TECH
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May 2014 In the absence of any friction and other irreversibilities, can a heat engine have an efficiency of 100 percent?
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In a complete cycle, what is the net change in energy and volume?Very Short Answer 2 Marks May-2014 • PTU B-TECH
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The entropy of a hot baked potato decreases as it cools. Is this a violation of the increase of entropy principle? Explain.Short Answer 2 Marks May-2014 • PTU B-TECH
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Ice cubes in a glass of liquid water will eventually melt and all the water approach room temperature. Is this a reversible process? Why?Short Answer 2 Marks May-2014 • PTU B-TECH
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The moment of inertia of a triangular section of base b and height h about an axis passing through its vertex and parallel to its base is ______ times as that passing through its centre of gravity and parallel to its base.Fill in the Blanks 2 Marks May-2014 • PTU B-TECH
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State the purpose of piston rings and crank shaft in an I.C. engine.Short Answer 2 Marks May-2014 • PTU B-TECH
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Dec 2016 What is the function of crank shaft and flywheel in an IC engine?
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Dec 2011 State the purpose of cam shaft and piston rings in an I.C. engine?
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Dec 2011 State the purpose of cam shaft and flywheel in an I.C. engine.
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Name any four mechanical properties of metals and corresponding tests to find them.Short Answer 2 Marks May-2014 • PTU B-TECH
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What are composites? Name any four along with their applications.Short Answer 2 Marks May-2014 • PTU B-TECH
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Dec 2017 What are various kinds of composite materials? State their industrial applications.
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A piston cylinder device contains unit mass of a fluid at 20 atm and 0.04 m3. The fluid is expanded reversibly according to the law pV^1.5 = C until the volume becomes 2 times that of its initial value. The fluid is then cooled reversibly at constant pressure until the piston comes back to its original position. Now, heat is supplied reversibly with the piston locked in position until the pressure rises to the original value of 20 atm. Calculate the net work done by the fluid.Long Answer May-2014 • PTU B-TECH
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Justify the statement that work and heat are not properties.Short Answer May-2014 • PTU B-TECH
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Oxygen passes through an adiabatic steady flow compressor at the rate of 1000 kg/h, entering as saturated vapour at 2.5 atm and emerging at 17.5 atm and 175 K. Find the shaft power required per kg of oxygen and the required power of the motor to run the compressor. Treat oxygen as an ideal gas and take y = 1.4.Long Answer 8 Marks May-2014 • PTU B-TECH
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Prove that the COP of a reversible refrigerator operating between two given temperatures is the maximum.Long Answer May-2014 • PTU B-TECH
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A reversible engine operates between temperatures T1 and T2 (T1 > T2). The energy rejected from the engine is received by a second reversible engine at the same temperature T2. The second engine rejects energy at temperature T3 (T3 < T2). Show that the temperature T2 is the arithmetic mean of temperatures T1 and T3 if the engine produces the same amount of work output.Long Answer May-2014 • PTU B-TECH
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Define the term entropy. Show that entropy is a property of the system.Long Answer May-2014 • PTU B-TECH
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Dec 2023 a) Define entropy and prove that it is property of a system.
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May 2012 Define the term entropy. Show that entropy is a property of the system.
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1 kg of ice at -5°C is exposed to the atmosphere, which is at 20°C. The ice melts, and comes to thermal equilibrium with the surroundings. Determine the entropy increase of the universe. Take Cp(ice) = 2.093 kJ/kg-K and the latent heat of fusion of ice = 334 kJ/kg.Long Answer May-2014 • PTU B-TECH
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What do you mean by air standard cycles? What are the assumptions for air standard cycles?Short Answer May-2014 • PTU B-TECH
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May 2016 What is an air standard cycle?
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May 2013 What is an air standard cycle? Why are such cycles conceived?
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May 2008 What do you mean by air standard cycles?
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An engine working on air standard Otto cycle in which the salient points are 1, 2, 3 and 4 has upper and lower temperature limits T1 and T2. If the maximum work per kg of air is to be done, show that the intermediate temperature T3 = √(T1T2).Long Answer May-2014 • PTU B-TECH
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Find the centroid of a lamina as shown in figure.Long Answer 4 Marks May-2014 • PTU B-TECH
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Find the moment of inertia for a triangular lamina about (a) centroidal axis parallel to the base, (b) the base.Long Answer May-2014 • PTU B-TECH
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Differentiate between: (a) Creep and fatigue, (b) Ductility and malleability, (c) Elastic limit and proportional limit, (d) Yield stress and proof stress.Long Answer 4 Marks May-2014 • PTU B-TECH
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Briefly describe the selection procedure of materials.Short Answer 4 Marks May-2014 • PTU B-TECH
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Discuss the difference between theoretical and actual p–V diagrams for four stroke S.I. and C.I. engines.Long Answer 8 Marks May-2014 • 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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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 Diesel 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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In an engine based on Carnot cycle 0.6 kg of air is used giving a thermal efficiency of 60 percent. During isothermal expansion the heat transfer is 50 kJ. At the start of isothermal expansion, the pressure is 7 bar and the volume is 0.125 m3. Calculate: (a) the maximum and the minimum temperature for the cycle, (b) volume at the end of isothermal expansion, (c) heat transfer during each of the four processes. Take Cv = 0.718 kJ/kg-K and Cp = 1.005 kJ/kg-K.Long Answer 8 Marks May-2014 • PTU B-TECH
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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.