Solved question paper for EME Dec-2012 (B-TECH 1st-2nd)
Solved Question Paper
Elements of mechanical engineering Dec-2012
PTU • B-TECH • Civil 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-
Why are shape, colour and odour irrelevant in thermodynamics?Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Set up an expression for the displacement work done during an arbitrary process.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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May 2016 Set up an expression for the displacement work done during any arbitrary process.
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May 2016 Set up an expression for the displacement work done during any arbitrary process.
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May 2013 Set up an expression for the displacement work done during any arbitrary process.
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How does a control volume differ from a system?Short Answer 2 Marks Dec-2012 • PTU B-TECH
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May 2012 Define control volume and control surface. How does control volume differ from an open system?
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Comment on the validity of the statement: “All reversible engines operating between the same two thermal reservoirs have the same efficiency.”Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Dec 2016 Comment on the validity of the statement: All reversible engines operating between the same two thermal reservoirs have the same efficiency.
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May 2014 Verify the statement “The efficiency of an irreversible engine is always less than the efficiency of reversible one operating between the same two thermal reservoirs”.
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Write the expression for heat transfer which is equivalent to the term pdv for work transfer.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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What is cutoff ratio? How does it affect the air standard efficiency of a Diesel cycle?Short Answer 2 Marks Dec-2012 • PTU B-TECH
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May 2009 What is cut-off ratio? How it affects the air standard efficiency of diesel cycle?
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What are the two basic types of internal combustion engines? What are the fundamental differences between the two?Short Answer 2 Marks Dec-2012 • PTU B-TECH
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May 2016 How IC engines are classified?
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May 2012 How are internal combustion engines classified?
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Dec 2011 How internal combustion engines can be classified on the basis of cylinder arrangement?
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How does a machine help to achieve gain in force?Short Answer 2 Marks Dec-2012 • PTU B-TECH
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State the principle of superposition and point out its utility.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Define direct, shear and volumetric stresses and corresponding strains.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Determine the molecular weight of a gas if its specific heats are cp = 2.286 kj/kg – K and cv = 1.768 kj/kg – K.Short Answer 4 Marks Dec-2012 • PTU B-TECH
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One mole of an ideal gas at 10 bar and 300 K at constant pressure till the volume is doubled and then it is allowed to expand at constant temperature till the volume is doubled again. Calculate the work done by the gas.Long Answer 4 Marks Dec-2012 • PTU B-TECH
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Show that when an ideal gas is compressed in a piston cylinder assembly according to polytropic law pV n = C, the heat rejected, increase in internal energy and work done are in the ratio (γ–n) : (n – 1):(γ – 1).Long Answer 4 Marks Dec-2012 • PTU B-TECH
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What is the concept of continuum? How density and pressure are defined using this concept.Short Answer 4 Marks Dec-2012 • PTU B-TECH
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May 2018 What is the concept of continuum? How density and pressure are defined using this concept?
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Dec 2016 What is the concept of continuum? How density and pressure are defined using this concept?
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May 2013 What is the concept of continuum? How will you define density and pressure using this concept?
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Make an energy analysis of a turbine.Short Answer 2 Marks Dec-2012 • PTU B-TECH
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Steam enters a steam turbine at 5m elevation, at a velocity of 30m/s, enthalpy 2950 kJ/kg. At exit the velocity is 600 m/s, enthalpy 2200 kJ/kg and elevation 2m, 75 kJ/kg of heat is lost to the surroundings. Calculate the work output of the turbine.Long Answer 6 Marks Dec-2012 • PTU B-TECH
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May 2012 Steam enters a steam turbine at 5 m elevation, at a velocity of 30 m/s, enthalpy 2950 kJ/kg. At exit, the velocity is 600 m/s, enthalpy 2200 kJ/kg and elevation 2 m. 75 kJ/kg of heat is lost to the surroundings. Calculate the work output of the turbine.
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Dec 2011 The mass rate of flow into a steam turbine is 1.5 kg/s, and the heat transfer from the turbine is 8.5 kW. The following data are known for the steam entering and leaving the turbine: Inlet enthalpy 3137.0 kJ/kg, velocity 50 m/s, elevation above reference plane 6 m; Outlet enthalpy 2675.5 kJ/kg, velocity 200 m/s, elevation above reference plane 3 m. Find the power output of the turbine.
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A reversible engine operates between three heat reservoirs X, Y, and Z. The engine receives equal amount of heat from reservoir X and Y at temperatures Tx and Ty respectively and rejects heat to a reservoir Z at temperature Tz. If the efficiency of the engine is β times the efficiency of a reversible engine operating between two reservoirs X and Z only, show that Tx/Ty = 2(1–β) Tx/Tz + (2β–1).Long Answer 8 Marks Dec-2012 • PTU B-TECH
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A six cylinder four stoke Diesel engine has compression ratio 16 to 1. The bore and stroke are 200 mm and 250 mm respectively and the engine runs at 1200 rpm. Ambient conditions are 100kPa and 300 K. Calculate the power produced if the cut off is 10% of the stroke. What is the maximum temperature?Long Answer 8 Marks Dec-2012 • PTU B-TECH
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A substance is initially at 0.5 MPa pressure and 0.25m3. It is compressed by an isentropic process so that the final pressure is 3 MPa. Find changes in enthalpy, internal energy and entropy, and heat and work interactions during the process.Long Answer 8 Marks Dec-2012 • PTU B-TECH
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A vertical circular copper bar 20mm diameter and 3m long carries a tensile load of 200kN. Calculate the elongation, decrease in diameter and the volumetric strain.Long Answer 8 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 Petrol 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 Diesel 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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Sketch and describe the working of crank and slotted lever type quick return mechanism.Long Answer 4 Marks Dec-2012 • PTU B-TECH
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May 2014 Discuss working of a crank and slotted lever type of quick return mechanism with a neat sketch and explain its working.
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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.