Solved question paper for EME May-2011 (B-TECH 1st-2nd)
Solved Question Paper
Elements of mechanical engineering May-2011
PTU • B-TECH • Mechanical Engineering • 1st-2nd • May-2011
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-
With same compression ratio, an engine working on Dual, Diesel or Otto cycle is most efficient. Select the correct cycle.MCQ 2 Marks May-2011 • PTU B-TECH
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Starting from the same initial state, plot constant volume and constant pressure heat addition processes on the T-S coordinates along with arrow-heads indicating the direction of the processes, and identify these two processes on the T-S chart.Short Answer 2 Marks May-2011 • PTU B-TECH
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What is the fundamental and basic difference between the terms enthalpy and total energy associated with the mass of a thermodynamic medium?Short Answer 2 Marks May-2011 • PTU B-TECH
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May 2011 What is the difference between total energy and enthalpy? Express both terms in detail.
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May 2011 How enthalpy differs from the term heat transfer? Explain the difference between the two in detail.
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May 2010 Define enthalpy of the system. How is it related to internal energy?
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Dec 2005 How enthalpy is related to the internal energy?
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Justify by assigning some numerical values, through a practical example, that dQ is not equal to dW for an irreversible heat exchange process; for example, by considering irreversible heat addition to a heat engine.Short Answer 2 Marks May-2011 • PTU B-TECH
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Starting from the same initial state, plot reversible and irreversible adiabatic expansion processes on T-S coordinates along with arrow-heads indicating the direction of the processes. Show the area which represents the fraction of energy that becomes unavailable during the irreversible process.Short Answer 2 Marks May-2011 • PTU B-TECH
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May 2011 Starting from the same initial state 1, plot a reversible and an irreversible adiabatic compression processes on T-S coordinates with arrow heads indicating the direction of the two processes. Show the area which is representative of the fraction of energy which became unavailable during this irreversible process.
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Can the COP of a refrigerator be greater than, less than, or both greater than as well as less than unity? Select the correct answer, and justify your reply by assigning numerical values to the cooling effect and the compressor work using a simple real-life practical example.MCQ 2 Marks May-2011 • PTU B-TECH
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Can throttling process be plotted on p-v coordinates? Give answer in YES or NO and give reasons for the same.True / False 2 Marks May-2011 • PTU B-TECH
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Super-impose a Carnot cycle on a Diesel cycle plotted on the T-S coordinates, such that the end-states representing the lowest and highest temperatures for the two cycles are coinciding with each other. Illustrate with the aid of T-S coordinates that the Diesel cycle operating between the same lowest and highest temperature limits will be less efficient than the corresponding Carnot cycle.Short Answer 2 Marks May-2011 • PTU B-TECH
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During free expansion process, temperature decreases, increases or remains constant. Select the correct answer.MCQ 2 Marks May-2011 • PTU B-TECH
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Dec 2019 Temperature (increases / decreases / remains constant) during free expansion process.
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Define temperature stresses and strains.Short Answer 2 Marks May-2011 • PTU B-TECH
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Dec 2016 What is thermal stress?
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May 2010 Define temperature stresses and strains.
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Dec 2009 What are temperature stresses?
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How enthalpy differs from the term heat transfer? Explain the difference between the two in detail.Long Answer May-2011 • PTU B-TECH
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May 2011 What is the difference between total energy and enthalpy? Express both terms in detail.
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May 2011 What is the fundamental and basic difference between the terms enthalpy and total energy associated with the mass of a thermodynamic medium?
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May 2010 Define enthalpy of the system. How is it related to internal energy?
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Dec 2005 How enthalpy is related to the internal energy?
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One of the essential requirements for accomplishing any reversible expansion process is that there should be complete thermal equilibrium between the system and the thermal reservoir exchanging heat during the process. Justify the above statement by thermodynamic or any other logic.Long Answer May-2011 • PTU B-TECH
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Is the equation dQ = dU - Vdp valid for a process occurring in an open system, in a closed system, or in both systems? Select the correct answer.MCQ May-2011 • PTU B-TECH
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May 2011 dQ = dE + PdV ... Is this equation valid for a process occurring in an open system, or in a closed system, or in both? What is PdV?
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The properties of a certain gas are related as follows: E = 196 + 0.718 t and Pv = 0.287 (t + 273), where E is the specific internal energy (kJ/kg), t is in °C, p is pressure in kN/m² and v is specific volume (m³/kg). Determine the two specific heats C_v and C_p for this gas.Long Answer May-2011 • PTU B-TECH
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Select suitable coordinates for plotting free expansion process and plot it on those coordinates along with an arrow-head indicating the direction of the process.Short Answer May-2011 • PTU B-TECH
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Air at 1 bar and 7°C is heated at constant volume in a cylinder till its temperature has risen to 821°C. It is then expanded isentropically to 1 bar and subsequently heat is rejected at constant pressure until the temperature is again equal to 7°C. Determine per kg of air: (i) pressure, volume and temperature at the end of each process, (ii) heat supplied to the cycle, (iii) work delivered by the cycle, and (iv) efficiency of the cycle.Long Answer May-2011 • PTU B-TECH
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May 2007 A quantity of air at 1 bar and 7ºC is heated at constant volume in a cylinder until its temperature has risen to 827ºC. After this it is expanded isentropically until the pressure falls to 1 bar following which heat is rejected at constant pressure until the temperature is again equal to 7ºC. Determine, per kg of air, the pressure, volume and temperature at the end of each of the operations.
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May 2007 A quantity of air at 1 bar and 7ºC is heated at constant volume in a cylinder until its temperature has risen to 827ºC. After this it is expanded isentropically until the pressure falls to 1 bar following which heat is rejected at constant pressure until the temperature is again equal to 7ºC. Determine, per kg of air, the heat input to the cycle.
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May 2007 A quantity of air at 1 bar and 7ºC is heated at constant volume in a cylinder until its temperature has risen to 827ºC. After this it is expanded isentropically until the pressure falls to 1 bar following which heat is rejected at constant pressure until the temperature is again equal to 7ºC. Determine, per kg of air, the work output of the cycle.
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May 2007 A quantity of air at 1 bar and 7ºC is heated at constant volume in a cylinder until its temperature has risen to 827ºC. After this it is expanded isentropically until the pressure falls to 1 bar following which heat is rejected at constant pressure until the temperature is again equal to 7ºC. Determine, per kg of air, the efficiency of the cycle.
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An irreversible engine takes 1200 kW from a reservoir at 700 K and develops 200 kW of work when executing complete cycles. The engine rejects heat to two reservoirs at 600 K and 500 K. Determine heat rejected to both the reservoirs. Draw a schematic line sketch for the engine and plot the cycle for this engine on T-S coordinates.Long Answer May-2011 • PTU B-TECH
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Explain and justify how isothermal heat addition process contributes in optimizing the output and hence efficiency of the Carnot cycle.Long Answer May-2011 • PTU B-TECH
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May 2011 Explain and justify how isentropic expansion process contributes in maximising the output and hence efficiency of the Carnot cycle.
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Which is the more effective method of increasing the efficiency of a Carnot cycle out of the following two possibilities: (i) by increasing T1 while maintaining T2 constant, or (ii) by decreasing T2 while maintaining T1 constant (T1 > T2)? Arrive at your decision with the help of T-S chart.Long Answer May-2011 • PTU B-TECH
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May 2018 Which is more effective way to increase the efficiency of a Carnot heat engine: to increase the source temperature T1, while the sink temperature T2 is held constant, or to decrease the sink temperature by the same amount while the source temperature is held constant? How this result would be affected in case of a Carnot heat pump?
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In an air standard Brayton cycle, the air enters the compressor at 1 bar and 25°C. The pressure after compression is 3 bar. The temperature at turbine inlet is 650°C. Calculate per kg of air: (a) heat supplied, (b) heat rejected, (c) net work done, (d) temperature of air leaving the turbine, (e) air-standard efficiency of the cycle, and (f) work ratio of the unit.Long Answer May-2011 • PTU B-TECH
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Write brief notes on differential wheel and axle.Short Answer May-2011 • PTU B-TECH
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May 2008 Write notes on Differential wheel and axle.
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Write brief notes on lifting machines.Short Answer May-2011 • PTU B-TECH
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May 2008 Write notes on Lifting machines.
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Write brief notes on worm and worm wheel.Short Answer May-2011 • PTU B-TECH
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Dec 2008 Write notes on worm and worm wheel.
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Make a labeled sketch of the Oldham coupling and list its uses.Short Answer May-2011 • PTU B-TECH
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May 2013 Make a labelled sketch of Oldham Coupling.
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Dec 2010 Make a labelled sketch of Oldham coupling?
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Define kinematic link, kinematic pair and kinematic chain.Short Answer May-2011 • PTU B-TECH
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May 2017 What is kinematic chain?
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May 2017 State different types of basic kinematic chain.
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Dec 2014 What is kinematic chain?
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May 2013 Define link, kinematic chain with example.
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May 2012 What are kinematic links? How are they classified?
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Dec 2010 What is kinematic link.
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Dec 2009 Define kinematic link, kinematic pair and kinematic chain.
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Dec 2007 Define link, kinematic chain with example.
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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.