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-
Minimum number of processes required to complete a workable ideal heat engine cycle are: 1, 2, 3, 4, 5, 6... (Select the correct answer)MCQ 2 Marks May-2011 • PTU B-TECH
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Why is a constant volume process line steeper than the constant pressure process line on the T-S coordinates? Explain the reason in two or three lines with the aid of T-S charts, or otherwise.Short Answer 2 Marks May-2011 • PTU B-TECH
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COP, which de facto implies the efficiency of a heat pump, is always greater than unity. But on the contrary, the efficiency of any system (including heat pump) cannot be more than 100%, otherwise the basic laws of thermodynamics would fail. Justify in two to three lines that true efficiency even in case of a heat pump cannot be more than 100%.Short Answer 2 Marks May-2011 • PTU B-TECH
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Substantiate by giving some live example with numerical values or otherwise, that dS > dQ/T (where dQ is irreversible heat exchange) for an irreversible heat exchange process, say, for the case of irreversible heat rejection dQ from a heat engine to the sink (atmosphere).Short Answer 2 Marks May-2011 • PTU B-TECH
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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.Short Answer 2 Marks May-2011 • PTU B-TECH
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May 2011 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.
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Prove that two adiabatic processes cannot cut each other; i.e., they cannot have a common state.Short Answer 2 Marks May-2011 • PTU B-TECH
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Can free expansion process be plotted on P-V coordinates? Give answer in YES or NO and give reasons for the same.Short Answer 2 Marks May-2011 • PTU B-TECH
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Fuel used in an engine operating on Otto cycle (i.e., constant volume heat addition cycle) is petrol because ________.Fill in the Blanks 2 Marks May-2011 • PTU B-TECH
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Temperature decreases/increases/remains constant during throttling process. (Select the correct answer)MCQ 2 Marks May-2011 • PTU B-TECH
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Sketch stress-strain curves for ductile and brittle materials and show the salient points on it.Long Answer 2 Marks May-2011 • PTU B-TECH
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May 2015 Draw and explain the stress-strain diagram for mild steel? Also describe how it is different from brittle materials.
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Dec 2010 Sketch a Stress-Strain for ductile and brittle materials and show the salient point on it.
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May 2007 Draw stress strain curve for a typical brittle material.
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Dec 2005 Draw a stress-strain curve for a mild steel specimen.
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What is the difference between total energy and enthalpy? Express both terms in detail.Long Answer 10 Marks May-2011 • PTU B-TECH
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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 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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'One of the requirements for a process to become most efficient or reversible process is that it should be carried out in the system under complete thermodynamic equilibrium conditions.' Justify and substantiate the above statement by thermodynamic or any other logics.Long Answer 10 Marks May-2011 • PTU B-TECH
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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?Long Answer 10 Marks May-2011 • PTU B-TECH
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May 2011 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.
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A mass of 10 kg at room temperature is dropped from a height of 100 m into a pond containing 1000 kg of water at room temperature. Calculate the change in internal, potential and kinetic energies, heat and work transfer for the following three cases: (i) Stone is just about to strike the water. (ii) Stone just after striking the water, stopped immediately at the bottom of pond. (iii) Stone achieves the ambient temperature after reasonable amount of time.Long Answer 10 Marks May-2011 • PTU B-TECH
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Dec 2007 A mass of 10 kg at room temperature is dropped from a height of 10 m into a bucket at room temperature containing 200 kg of water. Calculate the change in internal, potential and kinetic energies, heat and work transfer for case (a): Stone is just about to strike the water.
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Dec 2007 A mass of 10 kg at room temperature is dropped from a height of 10 m into a bucket at room temperature containing 200 kg of water. Calculate the change in internal, potential and kinetic energies, heat and work transfer for case (b): Stone just stopped at bottom of bucket.
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Select suitable coordinates for plotting throttling process, and plot it on these coordinates along with an arrow-head indicating the direction of the process.Short Answer 10 Marks May-2011 • PTU B-TECH
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A 0.2 m^3 of ideal gas at a pressure of 20 bar and 600 K is expanded isothermally to 1 m^3. It is then cooled to 300 K at constant volume and then compressed back polytropically to its initial state. Find net work done and the net heat transfer during the cycle.Long Answer 10 Marks May-2011 • PTU B-TECH
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May 2023 0.15m3 of an ideal gas at a pressure of 15 bar and 550K is expanded isothermally to 4 times the initial volume. It is then cooled at 290K at constant volume and then compressed back polytropically to its initial state. Calculate the net work done and heat transferred during the cycle.
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Dec 2020 0.15 m^3 of an ideal gas at a pressure of 15 bar and 550 K is expanded isothermally to 4 times the initial volume. It is then cooled at 290 K at constant volume and then compressed back polytropically to its initial state. Calculate the net work done and heat transferred during the cycle.
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May 2010 0.2 m3 of an ideal gas at a pressure of 2 MPa and 600 K is expanded isothermally to 5 times the initial volume. It is then cooled to 300 K at constant volume and then compressed back polytropically to its initial state. Determine the net work done and heat transfer during the cycle.
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A Carnot engine operating between a heat reservoir at T1 and cold reservoir at T2 is to drive a Carnot refrigerator removing heat Qc from a reservoir at a temperature Tc and rejecting the heat at T2. What is the minimum amount of heat Q1 that is to be taken out from the hot body at T1 to remove Qc from coolest reservoir? Given: T1 > T2 > Tc.Long Answer 10 Marks May-2011 • PTU B-TECH
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If T1 = 800 K, T2 = 310 K, Tc = 210 K, determine the minimum value of Q1 if Qc is 100 kW and heat is rejected by the heat pump at temperature T2.Long Answer 10 Marks May-2011 • PTU B-TECH
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Explain and justify how isentropic expansion process contributes in maximising the output and hence efficiency of the Carnot cycle.Long Answer 10 Marks May-2011 • PTU B-TECH
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May 2011 Explain and justify how isothermal heat addition process contributes in optimizing the output and hence efficiency of the Carnot cycle.
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Why is a diesel engine less efficient as compared to the Carnot cycle, when both are operating between the same temperature limits? Explain it with the aid of T-S diagrams for the two cycles.Long Answer 10 Marks May-2011 • PTU B-TECH
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In an air standard diesel cycle, the compression ratio is 15 and the pressure and temperature of air at the beginning of the compression are 1 bar and 288 K. The peak temperature in the cycle is 2700 K. Determine: (a) heat supplied, (b) work done, (c) cycle efficiency, (d) peak pressure of the cycle, (e) cut off ratio, (f) M.E.P.Long Answer 10 Marks May-2011 • PTU B-TECH
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Dec 2009 In an air standard diesel cycle, the compression ratio is 15 and the pressure and temperature of the air at the beginning of the compression are 1 bar and 288 K. The peak temperature in the cycle is 2700 K. Calculate the heat supplied.
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Dec 2009 In an air standard diesel cycle, the compression ratio is 15 and the pressure and temperature of the air at the beginning of the compression are 1 bar and 288 K. The peak temperature in the cycle is 2700 K. Calculate the work done.
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Dec 2009 In an air standard diesel cycle, the compression ratio is 15 and the pressure and temperature of the air at the beginning of the compression are 1 bar and 288 K. The peak temperature in the cycle is 2700 K. Calculate the cycle efficiency.
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Dec 2009 In an air standard diesel cycle, the compression ratio is 15 and the pressure and temperature of the air at the beginning of the compression are 1 bar and 288 K. The peak temperature in the cycle is 2700 K. Calculate the peak pressure of the cycle.
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Dec 2009 In an air standard diesel cycle, the compression ratio is 15 and the pressure and temperature of the air at the beginning of the compression are 1 bar and 288 K. The peak temperature in the cycle is 2700 K. Calculate the cut-off ratio.
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Dec 2009 In an air standard diesel cycle, the compression ratio is 15 and the pressure and temperature of the air at the beginning of the compression are 1 bar and 288 K. The peak temperature in the cycle is 2700 K. Calculate the mean effective pressure.
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Discuss various inversions of double slider crank chain mechanism.Long Answer 10 Marks May-2011 • PTU B-TECH
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May 2018 Sketch and briefly explain any two inversions of a double slider crank chain.
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Dec 2010 Discuss the various inversion of double slider crank chain mechanism.
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Explain longitudinal and lateral strain, Poisson's ratio, yield point and bulk modulus.Long Answer 10 Marks May-2011 • PTU B-TECH
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May 2008 Explain longitudinal strain, Poission\'s ratio, yield point and bulk modulus.
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Dec 2008 Explain lateral strain, Young\'s modulus of elasticity and stress-strain curve.
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FAQ
Frequently Asked Questions
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.