Solved question paper for EME Dec-2011 (B-TECH 1st-2nd)
Solved Question Paper
Elements of mechanical engineering Dec-2011
PTU • B-TECH • Mechanical Engineering • 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-
On a hot summer day, a student turns his fan on when he leaves his room in the morning. When he returns in the evening, will the room be warmer or cooler than the neighboring rooms? Why? Assume all the door and windows are kept closed.Short Answer 2 Marks Dec-2011 • PTU B-TECH
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Dec 2023
On a hot summer day, a student turns his fan on when he leaves his room in the morning. When he returns in the evening, will the room be warmer or cooler than the neighboring rooms? Why? Assume all the door and windows are kept closed.
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Can a steady state device have boundary work? Discuss.Short Answer 2 Marks Dec-2011 • PTU B-TECH
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If the efficiency of a power plant goes up as the low temperature drops why not let the heat rejection go to a refrigerator at say –10ºC instead of ambient 20ºC?Short Answer 2 Marks Dec-2011 • PTU B-TECH
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How internal combustion engines can be classified on the basis of cylinder arrangement?Short Answer 2 Marks Dec-2011 • 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 2012 What are the two basic types of internal combustion engines? What are the fundamental differences between the two?
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For the same maximum pressure and work output, 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 heat input, compare Otto cycle and Diesel cycle on P-v and T-s diagrams.
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What is the difference between a nozzle flow and a throttle process?Short Answer 2 Marks Dec-2011 • PTU B-TECH
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How does a lifting machine can lift more load than the applied load?Short Answer 2 Marks Dec-2011 • PTU B-TECH
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State the purpose of cam shaft and piston rings 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 flywheel in an I.C. engine.
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Draw neat sketches of any two inversions of four bar kinematic chain?Long Answer 2 Marks Dec-2011 • PTU B-TECH
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May 2014 Draw neat sketches of any two inversions of double slider kinematic chain.
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Differentiate between creep and fatigue?Short Answer 2 Marks Dec-2011 • PTU B-TECH
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May 2016 Differentiate between creep and fatigue.
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May 2009 Describe creep and fatigue.
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Dec 2007 Differentiate between creep and fatigue.
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An insulated vessel containing 5 kg of liquid water at 38ºC, 1 kg of ice at 0ºC is placed. Calculate the temperature of the water when the ice is completely melted. Take the latent heat of fusion of ice as 335 kJ/kg and specific heat of water as 4.19 kJ/kg–ºC.Long Answer Dec-2011 • PTU B-TECH
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A gas having mass 4.5 kg undergoes a process from 50ºC to 100ºC. If the specific heat of the gas is a function of temperature alone, calculate the heat transfer during the process for the relation Cp = 1.256 + 80/(T + 50) kJ/kg–K.Long Answer Dec-2011 • PTU B-TECH
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A reversible heat engine operates between two reservoirs at temperatures of 600ºC and 40ºC. The engine drives a reversible refrigerator, which operates between 40ºC and -20ºC. The heat transfer to the engine is 2000 kJ and the network output from the combined engine and the refrigerator system is 360 kJ. Calculate heat transfer to the refrigerator and net heat transfer to the reservoir at 40ºC.Long Answer Dec-2011 • PTU B-TECH
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Dec 2019 A reversible heat engine operates between two reservoirs at temperatures 700°C and 50°C. The engine drives a reversible refrigerator which operates between reservoirs at temperatures of 50°C and — 25°C. The heat transfer to the engine is 2500 kJ and the net work output of the combined engine refrigerator plant is 400 kJ. Determine the heat transfer to the refrigerant and the net heat transfer to the reservoir at 50°C.
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List down the factors that render a process to be irreversible.Short Answer Dec-2011 • PTU B-TECH
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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.Long Answer Dec-2011 • 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 2012 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.
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Why specific heat of air at constant pressure is greater than specific heat at constant volume?Short Answer Dec-2011 • PTU B-TECH
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2 kg of water at 367 K is mixed with 3 kg of water at 283 K in an isolated system. Calculate the change in entropy due to mixing process.Long Answer Dec-2011 • PTU B-TECH
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Show that the change of entropy during a polytropic process for a perfect gas per unit mass is given as s_v ((γ - n)/(n - 1)) ln(T1/T2).Long Answer Dec-2011 • PTU B-TECH
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Prove that the optimum pressure ratio rp for maximum net work done between the temperatures T1 and T3 for a Brayton cycle is given by rp = (T3/T1)^(γ/2(γ-1)).Long Answer Dec-2011 • PTU B-TECH
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A diesel engine operating on diesel cycle has 20 cm bore and 30 cm stroke. The clearance volume is 420 cm3. The fuel is injected at constant pressure for 5% of the stroke. Calculate the air standard efficiency. If the cutoff is delayed from 5% to 8%, what will be the percentage loss in efficiency. Assume same compression ration in both cases?Long Answer Dec-2011 • PTU B-TECH
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Establish a relation between Young’s modulus, modulus of rigidity and bulk modulus?Short Answer Dec-2011 • PTU B-TECH
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May 2010 Derive the relation between Bulk modulus (K), Young\'s modulus (E) and Poisson\'s ratio (1/m).
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A specimen of steel 20 mm diameter with a gauge length of 200 mm is tested to destruction. It has an extension of 0.25 mm under a load of 80 kN and the load at elastic limit is 102 kN. The maximum load is 130 kN. The total extension at fracture is 56 mm and diameter at neck is 15 mm. Find: i) The stress at elastic limit ii) Young’s modulus iii) Percentage elongation iv) Percentage reduction in area v) Ultimate tensile stressLong Answer Dec-2011 • PTU B-TECH
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In a lifting machine whose velocity ratio is 50, it was found that an effort of 100 N was necessary to lift a load of 4000 N. Is the machine reversible? If so, what effort could be removed so that the machine is at the point of reversing?Long Answer Dec-2011 • PTU B-TECH
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Explain the working of a pantograph with neat sketches.Long Answer Dec-2011 • PTU B-TECH
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Explain the working of two stroke C.I. engine with the help of neat sketches.Long Answer Dec-2011 • PTU B-TECH
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Dec 2023 Explain the construction and working of four stroke petrol engine.
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Dec 2019 Explain the working of two stroke petrol engine giving neat sketch.
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Dec 2018 Explain the working of a two-stroke petrol engine with the help of neat sketches. What are the demerits of two-stroke engines?
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May 2016 Write short notes on working of two stroke petrol engine.
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May 2013 Discuss briefly the working of a 4 Stroke Petrol engine.
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May 2012 Describe the working principle of a two stroke petrol engine with a neat diagram.
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May 2007 Explain the working of two stroke IC engine with neat sketches.
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Dec 2007 Explain the working of four stroke IC engine with neat sketches.
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A steel rod 1 cm in diameter is subjected to an axial load of 200 N. If the diameter of the bar is increased by 10%, find the change in strain energy per unit length of the rod.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.