GTU Elements of Mechanical Engg. - December 2014 Exam Question Paper

GTU First Year Engineering (Semester 1)
Elements of Mechanical Engg.
December 2014

Total marks: --
Total time: --

INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Answer the given MCQ.

1 (a) 1 The unit of work is
(a) N.m (b) Joule (c) kg.m² /s² (d) all the above

1 M

1 (a) 2 The function of ozone layer is
(a) protects the earth from harmful effect of ultraviolet rays
(b)increase the temperature of earth
(c)increases CO₂ in atmosphere
(d)none of the above

1 M

1 (a) 3 In the Polytropic Process PVⁿ = C, if n = ∞ , the process is called
(a) isochoric (b) isobaric (c) isothermal (d) adiabatic

1 M

1 (a) 4 Saturation temperature of steam increase
(a) With decrease in pressure (b) with increase in pressure
(c)is unaffected by pressure (d) none of the above

1 M

1 (a) 5 During adiabatic process
(a) heat transfer is zero (b) work transfer is zero (c) enthalpy remains constant
(d)enthalpy change is zero.

1 M

1 (a) 6 The processes of Carnot cycle are
(a)Two adiabatic and two constant volume (b)Two constant pressure and two constant volume (c)Two isothermal and two adiabatic (d)Two isothermal and two isentropic

1 M

1 (a) 7 The air standard cycle on which the petrol engine work is (a) Otto cycle (b) Carnot cycle (c) Joule cycle (d) Dual cycle

1 M

Answer the given MCQ.

1 (b) 1 Pump is a machine which is used to do
A) lift liquid from low height to higher elevation
B) To store liquid
C) To compress liquid
D) none of the above

1 M

1 (b) 2 Which of the following energy is converted into electricity in a Hydro power plant
A) Nuclear energy
B) Potential Energy of water
C) Thermal Energy
D) all of the above

1 M

1 (b) 3 Which of the following is a unit of Electric current
A) Ampere
B) Volt
C) Meter
D) kilogram

1 M

1 (b) 4 Which of the following instrument is used to measure length
A) Vernier calliper
B) Manometer
C) Thermometer
D) none of the above

1 M

1 (b) 5 In a simple gear train having two gears , if driving gear rotates in clockwise direction then driven gear rotates in
A) Clockwise direction
B) Anti clockwise direction
C) depend on size of gear
D) depend on no. of teeth

1 M

1 (b) 6 In a IC engine which energy is converted into mechanical energy
A) Chemical energy of fuel.
B) potential energy
C) kinetic energy
D) All of the above

1 M

1 (b) 7 which of the following instrument is used for drawing a straight lines
A) T- Square
B) French curves
C) Protractor
D) Compass

1 M

Answer the given MCQ.

1 (c) 1 Which of the following are boiler mountings?
(a) Economiser (b) Fusible Plug (c) Super heater (d) Air pre-heater

1 M

1 (c) 2 The function of steam stop valve is
(a) to regulate flow of steam from boiler to steam pipe
(b)to separate steam from water (c ) to collect steam from steam drum
(d)to provide safety of boiler

1 M

1 (c) 3 Petrol engine is
(a) Compression ignition engine (b) Spark ignition engine (c) mixed ignition engine (d) all of the above

1 M

1 (c) 4 Which of the following is a positive belt drive.
(a) V-belt (b) flat belt (c) Cross belt (d) timing belt

1 M

1 (c) 5 A 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 (c) 6 _________is the ability of a material to resist deformation under stress.
(a) strength (b) stiffness (c) hardness (d) brittleness

1 M

1 (c) 7 A one ton refrigeration system means that its refrigerating system is
(a) 50 KJ/min (b) 210 KJ/min (c) 300 KJ/min (d) 350 KJ/min

1 M

2 (a) Write a short note on solar energy?

3 M

2 (b) Explain Barrel calorimeter with neat sketch.

4 M

2 (c) One kg of gas is compressed polytropically from 160 kpa pressure and 280 K temperature to 760 KPa. The compression is according to law PV^1.3 = Constant. Find: (1) Final Temperature (2) work done (3) change in internal energy (4) amount of heat transfer and (5) change in enthalpy. Take R=0.287 KJ/KgK and C_p = 1.002 KJ/KgK.

7 M

3 (a) Show the function and location of the following in the boiler plant:
(i) Economiser (ii) Steam stop valve (iii) Fusible plug.

3 M

3 (b) Derive C_p -C_v =R, with usual notations.

4 M

3 (c) 1.5 kg of steam at a pressure of 10 bar and temperature of 250°C is expanded until the pressure becomes 2.8 bar. The dryness fraction of steam is then 0.9. Calculate change in internal energy.

7 M

4 (a) Compare Rankine cycle with Carnot cycle.

3 M

4 (b) In an Otto cycle the compression ratio is 10. The temperature at the beginning of compression and at the end of heat supply is 300 K and 1600 K respectively. Assume, γ = 1.4 and C_v = 0.717 KJ/KgK.
Find: (i) Heat supplied (ii) Efficiency of the cycle.

4 M

4 (c) Sketch and explain a Cochran boiler.

7 M

5 (a) Explain with the help of neat sketches, the working of two stroke petrol Engine.

7 M

5 (b) Derive an equation for air standard efficiency of Otto cycle.

7 M

6 (a) Explain working of a centrifugal pump.

3 M

6 (b) What is compressor? Give uses of compressed air.

4 M

6 (c) Explain Vapour Compression Refrigeration system with neat sketch. Also draw p-h and T-s diagram for the same.

7 M

7 (a) Define the following mechanical properties
(i) Ductility (ii) Hardness (iii) Plasticity

3 M

7 (b) What is belt drive? Describe briefly types of belt drives.

4 M

7 (c) What is coupling? Explain internal expanding shoe brake with a neat sketch?

7 M

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