VTU First Year Engineering (P Cycle) (Semester 2)
Elements of Mechanical Engg.
December 2011
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

Select the correct anser :-
1 (a) (i) The process in which using the principle of photo voltaic effect, the steam energy us directly converted into electrical energy is
(A) Helio eletrical process
(B) Helio thermal process
(C) Mechanical process
(D) none of these
1 M
1 (a) (ii) The difference between superheated temperature and the saturation temperature of steam is called
(A) Degree of superheat
(B) Latent heat vapourization
(C) Sensible heat
(D) None of these
1 M
1 (a) (iii) Quality of wet steam is decided by its
(A) Temperature
(B) Pressure
(C) Dryness fraction
(D) None of these
1 M
1 (a) (iv) Specific volume of superheated steam (V sup) with usual notations is
[ (A) =V_{g} imes dfrac {T_{sat}}{T_{sup}} \ (B) =V_{g} imes dfrac {T_{sup}}{T_{sat}} \(C) =V_{f} imes dfrac {T_{sat}}{T_{sup}} \(D) =V_{f} imes dfrac {T_{sup}}{T_{sat}} ]
1 M
1 (b) Differentiate between renewable and non-renewable source of energy.
6 M
1 (c) 10 Kg of wet steam of dryness fraction 0.8, passes from a boiler to superheater at a constant pressure of 1MPa. In the superheater its temperature increases to 340°C. Determine the amount of heat supplied in the superheater. Assume specific heat of superheated steam CP=2.25KJ/Kg°K.
10 M

Select the correct answer :-
2 (a) (i) Utilization of the high pressure energy of the steam by expanding it in successive stages is called.
(A) Impulse turbine
(B) Reaction turbine
(C) Compounding
(D) None of these
1 M
2 (a) (ii) Pelton wheel is a
(A) Law head impulse turbine
(B) Medium head impulse turbine
(C) High head impulse turbine
(D) Reaction turbine
1 M
2 (a) (iii) In case of impulse water turbine, the entire hydrro energy is converted into kinetic energy by passing the water through
(A) Tailrace
(B) Runner
(C) Nozzle
(D) None of these
1 M
2 (a) (iv) The cross-section of a draft tube in a turbine
(A) Is uniform
(B) Gradually
? Gradually increases towards the outlet
(D) None of these
1 M
2 (b) Explain the working principle of operation of impulse and reaction turbines.
6 M
2 (c) Sketch and explain the working of a pelton wheel.
10 M

Select the correct answer :-
3 (a) (i) In a four stroke C.I. engine, during suction stroke:
(A) Only air is sucked in
(B) Only diesel is sucked in
(C) Both air and diesel sucked in
(D) Either diesel or air is sucked in
1 M
3 (a) (ii) In two stroke engines, the number of revolutions made by the crank to complete one cycle is
(A) One
(B) Two
(C) Three
(D) Four

Q3 (a) (iii) The brake power of an engine is always ______ the indicated power
(A) Equal to
(B) Less than
(C) Greater than
(D) Reciprocal of
1 M
3 (a) (iv) The inner diameter of engine cylinder is called as
(A) Stroke
(B) Clearance
(C) Bore
(D) Pitch
1 M
3 (b) With neat sketches explain the working of 2-stroke petrol engine.
8 M
3 (c) A single cylinder 4-stroke I.C. engine has bore of 180 mm, stroke of 200 and a rated speed of 300 rpm. Torque on the brakedrum is 200N-m and mean effective pressure is 6bar, it consumes 4kg of fuel per hour. The calorificvalue of fuel is 42000 KJ/Kg. determine B.P, I.P, Brake thermal efficiency and mechanical efficiency.
8 M

Select the correct answer :-
4 (a) (i) An ideal refrigerant should have
(A) Low specific heat
(B) Low viscosity
(C) High thermal conductivity
(D) All of these
1 M
4 (a) (ii) The principle of refrigeration is based on
(A) Law of conservation of energy
(B) I Law of thermodynamics
(C) II Law of thermodynamics
(D) Zeroth law of thermodynamics
1 M
4 (a) (iii) The ratio of heat extracted from the refrigerator to the work done is called
(A) Performace ratio
(B) Thermal efficiency
(C) Co-efficient of performance
(D) Performance index
1 M
4 (a) (iv) The most commonly used refrigerant in vapour absorption refrigeration system is
(A) Freon
(B) CO2
(C) SO2
(D) NH3
1 M
4 (b) Explain Vapour Absorption refrigeration system.
8 M
4 (c) Explain room air conditioner system.
8 M

Select the correct answer :-
5 (a) (i) The process of thread cutting on a drilling machine is called as
(A) Spot facing
(B) Reaming
(C) Tapping
(D) Boring
1 M
5 (a) (ii) The operation of finishing the inner surface of a drilled hole in called as
(A) Spot facing
(B) Reaming
(C) Tapping
(D) Boring
1 M
5 (a) (iii) To drill a hole on a lathe, a drill bit is held in the
(A) Toolpost
(B) Tailstocks spindle
(C) Head stock
(D) Compound rest
1 M
5 (a) (iv) Which of these drilling machines is used for mass production ?
(A) Bench drilling machine
(B) Radial drilling machine
(C) Gang drilling machine
(D) Portable drilling machine
1 M
5 (b) Draw a neat sketch of a lathe and lable its parts.
10 M
5 (c) Differentiate between counter sinking and counter boring.
6 M

Select the correct answer :-
6 (a) (i) Irrugular shape of machines is done in
(A) Angular milling
(B) Form milling
(C) Gang milling
(D) End Milling
1 M
6 (a) (ii) _____ is a type of artificial abrasive.
(A) Sand stone
(B) Corundum
(C) Emery
(D) Aluminium oxide
1 M
6 (a) (iii) In vitrified bonding process, the abrasive grains are mixed with
(A) Clay and water
(B) Silicate of soda
(C) Shellac
(D) Rubber
1 M
6 (a) (iv) The horizontal shaft used to mount the milling cutter is called
(A) Spindle
(B) Connecting rod
(C) Saddle
(D) Arbor
1 M
6 (b) Draw a neat sketch of column and knee type horizontal milling machine and explain its working.
10 M
6 (c) Sketch and explain the following operations
(i) Surface grinding
(ii) Cylindrical grinding
6 M

Select the correct answer :-
7 (a) (i) Fusion welding is also known as _____
(A) Pressure welding
(B) Resistance welding
(C) Non-pressure welding
(D) Thermit welding
1 M
7 (a) (ii) The filler material material used in brazing is _____
(A) Solder
(B) Flux
(C) Spelter
(D) Electrode
1 M
7 (a) (iii) As the oil temperature increases, its viscosity _____
(A) Increases
(B) Decreases
(C) Will remain constant
(D) None of these
1 M
7 (a) (iv) A bearing in which the load acts along the axis of the shaft is called as
(A) Thrust bearing
(B) Journal bearing
(C) Roller bearing
(D) Ball bearing
1 M
7 (b) What are the desirable properties of a good lubricant ?
6 M
7 (c) Distinguish between soldering, brazing and welding.
10 M

Select the correct answer :-
8 (a) (i) The pulley which is used to increases the arc of contact is
(A) Stepped pulley
(B) Speed cone
(C) Jocky pulley
(D) Fast and loose pulley
1 M
8 (a) (ii) The ratio of speeds of the driver and driven pulley is
(A) Ratio to tensions
(B) Module
(C) Pitch circle diameter
(D) Velocity ratio
1 M
8 (a) (iii) The gear used to connect coplanar, parallel and Non-parallel axes shaft is
(A) Helical gear
(B) Spur gear
(C) Bevel gear
(D) Worm gear
1 M
8 (a) (iv) TO convert rotary motion into linear motion which of the following gear is used?
(A) Spur gear
(B) Bevel gear
(C) Racknad pinion
(D) None of these
1 M
8 (b) Define slip and creep with respect to belt drives.
6 M
8 (c) Mention the advantages and disadvantages of belt drive.
6 M
8 (d) A compound gear train is formed by 4 gears P.Q.R. and S. Gear P meshes gear Q and R meshes gear S. Gear Q and R are compounded P is connected to the driving shaft and S is connected to the driven shaft and power is transmitted, the details of the gears are given below. find speed of gear P. if gear S rotates ar 60 rpm.
Gear P Q R S
No of teeth 30 60 40 80
4 M

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