Solved question paper for EME Dec-2011 (B-TECH 1st-2nd)
Solved Question Paper
Elements of mechanical engineering Dec-2011
PTU • B-TECH • Information Technology • 1st-2nd • Dec-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-
An ideal gas goes through an expansion process where the volume doubles. Which process will lead to the larger work output: an isothermal process or a polytrophic process with n=1.25?Short Answer 2 Marks Dec-2011 • PTU B-TECH
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In an effort to conserve energy in a heat engine cycle, somebody suggests incorporating a refrigerator that will absorb some of the waste energy QL and transfer it to the energy source of the heat engine. Is this a smart idea? Explain.Short Answer 2 Marks Dec-2011 • PTU B-TECH
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Air at 500 K, 500 kPa is expanded to 100 kPa in two steady flow cases. Case one is a throttle and case two is a turbine. Which has the highest exit T? Why?Short Answer 2 Marks Dec-2011 • PTU B-TECH
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Assume a heat engine with a given QH. Can you say anything about QL if the engine is reversible? If it is irreversible?Short Answer 2 Marks Dec-2011 • PTU B-TECH
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Why is the Carnot cycle not suitable as an ideal cycle for all power producing cycle devices?Short Answer 2 Marks Dec-2011 • PTU B-TECH
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May 2018 Why Carnot cycle cannot be used practically?
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A substance is compressed adiabatically so P and T go up. Does that change S?Short Answer 2 Marks Dec-2011 • PTU B-TECH
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For the same maximum pressure and heat input, compare Otto cycle and Diesel cycle on P-v and T-s diagrams.Short Answer 2 Marks Dec-2011 • PTU B-TECH
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May 2014 For the same compression ratio and heat rejection, compare Otto cycle and Diesel cycle on P-v and T-s diagrams.
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May 2014 For the same peak pressure, peak temperature and heat rejection, compare Otto cycle and Diesel cycle on P-v and T-s diagrams.
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Dec 2011 For the same maximum pressure and work output, compare Otto cycle and Diesel cycle on P-v and T-s diagrams.
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What are the technological properties of metals and alloys? Name any four.Short Answer 2 Marks Dec-2011 • PTU B-TECH
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What are the smart materials? Name any two along with their applications.Short Answer 2 Marks Dec-2011 • PTU B-TECH
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State the purpose of cam shaft and flywheel in an I.C. engine.Short Answer 2 Marks Dec-2011 • 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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May 2014 State the purpose of piston rings and crank shaft in an I.C. 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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Fluid is confined in a cylinder by a spring loaded, frictionless piston so that the pressure in the fluid is a linear function of volume (p = a+bV). The internal energy of the fluid is given by U=34+3.15PV. Where U is in kJ, p is in kPa, and V is in m3. If the fluid changes from an initial state of 170 kPa, 0.03 m3 to a final state of 400 kPa, 0.06 m3, with no work other than that done on the piston, find the direction and magnitude of the work and heat transfer.Long Answer Dec-2011 • PTU B-TECH
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Air at 9 bar and 200°C is throttled to 5 bar before being expanded through a nozzle to a pressure of 1.1 bar. Assuming that the flow through the nozzle is reversible steady flow process, and that no heat is rejected. Calculate the velocity of air at nozzle outlet when the inlet velocity is 80 m/s.Long Answer Dec-2011 • PTU B-TECH
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A reversible engine operates between temperatures T1 and T (T1>T). The energy rejected from the engine is received by a second reversible engine at the same temperature T. The second engine rejects energy at temperature T2 (T2<T). Show that the temperature T is the geometric mean of temperatures T1 and T2 if the engines have the same mechanical efficiencies.Long Answer Dec-2011 • PTU B-TECH
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A source X can supply energy at the rate of 11000 kJ/min at 320°C. Another source Y can supply at the rate of 11000 kJ/min at 60°C. Which source X or Y would you choose, to supply energy to an ideal reversible engine, that is to produce a large amount of power, if the temperature of the surroundings is 4°C.Long Answer Dec-2011 • PTU B-TECH
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State and prove Clausius inequality.Long Answer Dec-2011 • PTU B-TECH
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Dec 2023 b) State and prove Clausius inequality.
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May 2016 Explain the concept of Clausius Inequality.
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Dec 2016 What is Clausius inequality?
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May 2012 State and prove Clausius inequality.
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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.Long Answer Dec-2011 • 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 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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Derive an expression for mean effective pressure of diesel cycle.Long Answer Dec-2011 • PTU B-TECH
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Dec 2020 Derive the expression for the efficiency of the Diesel cycle.
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Dec 2016 What is air standard efficiency? Write its expression for diesel cycle.
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Dec 2016 Derive the expression for the ideal efficiency of Diesel cycle.
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May 2015 Derive the efficiency equation for Diesel cycle.
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Dec 2014 Write down the expression for air standard efficiency for a diesel engine?
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May 2013 Derive an expression for the air standard efficiency and mean effective pressure of a Diesel cycle. State the assumptions made.
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May 2012 Derive an expression for efficiency and mean effective pressure for a Diesel cycle.
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Dec 2007 What is air standard efficiency? Write its expression for diesel cycle.
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A diesel engine has a compression ratio of 14. The fuel is cut-off at 0.08 of stroke. The relative efficiency is 52%. Find the mass of fuel of calorific value 41800 kJ/kg which would be required per kWh.Long Answer Dec-2011 • PTU B-TECH
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Prove the parallel axis theorem in the determination of moment of inertia of areas with the help of a neat sketch.Long Answer Dec-2011 • PTU B-TECH
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May 2019 Prove the parallel axis theorem in the determination of moment of inertia of areas with the help of a neat sketch.
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Find the centroid of a semicircular lamina of radius r.Long Answer Dec-2011 • PTU B-TECH
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What are ER and MR fluids? Discuss their properties and areas of applications.Long Answer Dec-2011 • PTU B-TECH
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Give the composition, properties and uses of following alloy steels: 1) Heat resisting steels 2) Spring steels 3) Stainless steels 4) High speed steels.Long Answer Dec-2011 • PTU B-TECH
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Discuss the difference between theoretical and actual p–V diagrams for two stroke S.I. and C.I. engines.Long Answer Dec-2011 • 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 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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An ideal air standard Brayton cycle operates with air. At the compressor inlet, the air is at 305 K and 1 bar. It is further compressed to 5.5 bar. The maximum cycle temperature is limited to 1050 K. The heat supplied is 10.5 MW. Find: i) Thermal efficiency of the cycle, ii) Work ratio, iii) Power output.Long Answer Dec-2011 • 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.