GTU First Year Engineering (Semester 1)
Elements of Mechanical Engg.
December 2015
Total marks: --
Total time: --
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Objective Question (MCQ)
1(a)1 Prime mover is a device which converts natural resources into ______ energy.
(a) With decrease in pressure
(b) with increase in pressure
(c) is unaffected by pressure
(d) none of the above
1 M
1(a)2 Zeroth law of thermodynamics forms the basis of measurement of the following.
(a) heat exchange
(b) work
(c) pressure
(d) Temperature
1 M
1(a)3 Polytropic expansion of a gas is given by the law
(a) pVn = C (b) pVγ = C (c) pV = C (d) pV0 = C
1 M
1(a)4 Behaviour of vapour can be determined by
(a) Boyles law
(b) Charles law
(c) Combined law
(d) none of the above
1 M
1(a)5 Bucket pump is a type of ______ pump.
(a) rotary
(b) Centrifugal
(c) reciprocating
(d) axial
1 M
1(a)6 Centrifugal compressor is suitable for producing?
(a) High pressure
(b) medium pressure
(c) low pressure
(d) all of the above
1 M
1(a)7 Spur gear has teeth______ to the axes of the gears.
(a) inclined
(b) parallel
(c) perpendicular
(d) any of the above
1 M
1(b)1 The energy absorbed by brakes is released in surrounding in form of
(a) heat energy
(b) kinetic energy
(c) potential energy
(d) pressure energy
1 M
1(b)2 Which engine produces more power for same compression ratio
(a) 4- stroke diesel engine
(b) 4- stroke petrol engine
(c) 2- stroke diesel engine
(d) 2- stroke petrol engine
1 M
1(b)3 The operation of filling passage ways with liquid from outside source before starting pumps is known as______ .
(a) cavitation
(b) cleaning
(c) priming
(d) chocking
1 M
1(b)4 One ton of refrigeration is equal to
(a) 221 kJ/min
(b) 420 kJ/min
(c) 600 kJ/min
(d) 210 kJ/min
1 M
1(b)5 Belt drive provides ______ flexibility compared to gear drive.
(a) more
(b) less
(c) same
(d) can't say
1 M
1(b)6 Which of the following elements is used to connect two shafts ______
(a) clutch
(b) brakes
(c) Couplings
(d) none of above
1 M
1(b)7 ______ is the characteristic of cast iron.
(a) ductile
(b) malleable
(c) very brittle
(d) all of the above
1 M

2(a) Write a short note on Global Warming
3 M
2(b) Define isothermal process. Derive the expression for work done, change in internal energy and heat transfer for this process.
4 M
2(c) One cubic meter of air at pressure of 1.5 bar and 80° C is compressed to final pressure 8 bar and volume 0.28 m3 . Determine (i) mass of air (ii) index of 'n' compression (iii) change in internal energy (iv) Heat transfer during compression. Take γ = 1.4 and R= 287 J/kgK.
7 M

3(a) Show the function and location of the following in the boiler plant:
(i) Feed check valve
(ii) Air superheater
(iii) Fusible plug.
3 M
3(b) Explain Throttling calorimeter with neat sketch and calculation of dryness fraction.
4 M
3(c) Sketch and explain a Babcock and Wilcox boiler.
7 M

4(a) Differentiate between Two stroke and Four stroke I.C engines.
3 M
4(b) Determine the quality of steam for the following cases:
(i) P= 10 bar, v = 0.180 m3 /kg
(ii) P= 10 bar, t= 200° C
(iii) P=25 bar , h = 2750 kJ/kg
4 M
4(c) Derive equation for air standard efficiency of Diesel cycle.
7 M

5(a) Explain the working principle of centrifugal pump.
3 M
5(b) The following data refers to a single cylinder 4 strokes petrol engine. Cylinder diameter = 30 cm, piston stroke = 40 cm, engine speed= 1400 r.p.m, indicated mean effective pressure = 5 bar, fuel consumption= 17.568 kg per hour, calorific value of the fuel is 45000 kJ/Kg; specific gravity of the fuel is 0.8. Determine the indicated thermal efficiency.
4 M
5(c) Explain Vapor Compression Refrigeration system with neat sketch. Also draw p-h and T-s diagram for the same.
7 M

6(a) Define air-conditioning. Classify the air conditioning system in detail.
3 M
6(b) Why multi-stage compression is required? Write advantages of the multi- staging compression.
4 M
6(c) What are the different types of couplings? Explain the centrifugal clutch.
7 M

7(a) Define the following mechanical properties
(i) Elasticity
(ii) Toughness
(iii) Ductility
3 M
7(b) Explain the working principle of vane pump with neat sketch?
4 M
7(c) What are bearings? Explain with neat sketch worm and worm wheel.
7 M

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