Mahatma Gandhi University (MGU) 2008 B.Tech Mechanical Engineering Basic - Question Paper
Attached!!!
B.TECH DEGREE EXAMINATION, MAY 2008
First year
Branch: Computer Science and Engineering
BASIC MECHANICAL ENGINEERING
Regular/Supplementary
Time: Three Hours Maximum:100Marks
Answer all questions
Part A
1.Diffenentiate closed system and open system. Give examples.
2.Calculate characteristic gas constant for oxygen.
3.What are the functions of piston crown in two-stroke petrol engine?
4.Explain the term ton of refrigeration.
5.In power transmission systems where were belts and gears are used?
6.What do you mean by 7x 10 ropes? What are the materials used for making ropes?
7.What are the pollutants from Nuclear power plant?
8.What do you understand by specific speed of hydraulic turbine?
10.What is rolling? With a neat sketch, explain three roll mill.
(10x4=40 marks)
Part B
11. (a)What is intensive property and extensive properties? From the following properties differentiate intensive and extensive properties
(i) Volume (ii) Kinetic energy (iii) Specific enthalpy (iv) Internal energy (v) Density (vi) Temperature (vii) Flow work (viii) Pressure
Or
(b) 1 kg of gas expands adiabatic ally and its temp. is observed to fall from 240 c to 115 c while the vol. Is doublwed.The gas does 90 kJ of work during the process .Determine The value of Cp and Cv.
12. (a)Explain the working principle of a four stroke diesel engine with neat sketch.
Or
(b) With a neat sketch, explain vapor compression refrigeration system.
13. (a)What are the different types of gears used in power transmission systems? Explain the situations where they used.
Or
(b) An open belt drive transmits power of 42 kW with a velocity of 7m/sec. Find the tensions on each side of the belt. if μ=0.25 and angle of lap is 170
14 (a) With a neat sketch explain Nuclear power plant.
Or
(b) Compare hydroelectric and steam power plants.
15(a) Explain the following (i) slab milling (ii) Face milling (iii) Form milling (iv) End milling (v) T-slot milling
Or
(b) Describe a milling machine with a neat sketch
ANSWER KEY
1. Closed system the system does not permit the transfer of mass across the boundary and permits the transfer of energy.
 |
Cylinder
Piston
 |
Movable boundary
 |
Fixed boundary
The boundary of a closed system may or may not change position
Open system
the system, which allows the transfer of mass and energy across the boundary.
Turbines and pumps are examples.
Mass out
 |
 |
 |
||||
 |
||||||
Steam turbine
Work
 |
|||
 |
|||
Mass in
2. Refer text book by J.Benjamin,Page No.1.17
3. Refer text book by J.Benjamin,Page No.2.5
4. Unit of Refrigeration:-
the rate of heat absorbed by the refrgn system from the
body to be cooled, equivalent to the latent heat of fusion of
one ton of ice from and at 00C in 24 hrs is called one ton of
refrgn. The STD unit of refrgn is ton of refrgn or ton
5. BELT DRIVE: - This type of drive is used when the power is to be transmitted from one shaft to other which are at a distance. Pulleys are mounted on the driver and driven/follower shafts and an endless belt is fitted tightly over these pulleys. The frictional resistance between these pulleys and belt is the reason for the power transmission, which depends on the velocity of belt, tension of the belt and arc of contact of the belt in the smaller pulley. There are flat belt and V- belt used for the power transmission.
GEAR DRIVES: -Toothed wheel is the gear for transmitting power between two shafts, which are very closer. The teeth of the gear mounted on the shaft meshes each other during rotation. Gears are manufactured either by milling, by casting or by hobbing. Spur gear, helical gear, bevel gear, worm gear are different types.
6. Refer text book by J.Benjamin,Page No.3.5.
7. Refer text book by J.Benjamin,Page No.4.15
8.It is the speed of the turbine , when it produces unit power when
working under unit head.
10.Refer text book by J.Benjamin,Page No.5.37
11.(a) Intensive and extensive property if the value of a property is independent of mass of the system then it is called intensive property. When the whole or part of the system is considered, if the value of the property remains the same it is again intensive property. If the value of the property is proportional to the mass of the system, it is called extensive property. Vol, energy. are examples
(b)Refer text book by J.Benjamin,Page No.1.46
12.(a) Refer text book by J.Benjamin,Page No.2.8
(b) Vapor compression system:- in this system the working fluid is readily evaporates and condenses. It evaporates absorbing heat from the space and rejects heat to the surroundings during condensing. The following are the basic components of a simple vapor compression system.
1. compressor
2. condenser
3. expansion valve
4. evaporator cooling
Water
|
||||
 |
||||
3
 |
 |
||||
 |
|||||
2 1
3 2
2
pr
4
Evaporator
1
 |
 |
4
 |
|||||
 |
|||||
 |
|||||
H brine solution
-10-
the line diagram of the system and its pr-enthalpy plotting is shown in the fig. The dry saturated vapor of the working fluid (Freon or R12) is entered in to the compressor at pr p1 and temp T1during its suction stroke and compressed isentropically to pr p2 and temp T2. The line 1-2 in the p-H diagram shows this process.
At the end of the compression, the high temp and high pr vapor is in the super heated state passes to the condenser through which water is circulated to receive heat from the vapor. The vapor is cooled to the saturation temp at 2 and at constant pr. The cooling continues till the vapor reached at 3 in the liquid phase at low temp and high pr. The latent heat of condensation removes from the vapor by this time. This high pr low temp liquid is allowed to expand by passing through an expansion valve. Now the pr and temp very low to p1. The expansion process 3-4 is a const enthalpy process. During throttling the liquid partly evaporates and gets a liquid vapor mixture at temp T1 and pr p1.
This vapor passes through the evaporator coil, which is surrounded by the items/liquid (brine solution) to be cooled. The refrigerant from the expansion valve will absorb heat of the brine solution in the evaporator and gets vaporized and reaches the dry saturated condition at 1and thus completing one cycle of operation.
The cold brine then circulated through coils around the space to be refrigerated. The net refrigerating effect of the system is heat absorbed by the refrigerant from the brine. The work done by the compressor is the heat added to the refrigerant during the compression process
Heat extracted from the brine
COP = --------------------------------------
Work done by the compressor
13.(a)Refer text book by J.Benjamin,Page No.3.7
(b) Refer text book by J.Benjamin,Page No.3.15
14.(a)Refer text book by J.Benjamin,Page No4.14
(b) Refer text book by J.Benjamin,Page No 4.11
15.(a)Refer text book by J.Benjamin,Page No5.19
(b) Refer text book by J.Benjamin,Page No5.14
B.TECH DEGREE EXAMINATION,MAY 2008
Fourth Semester
Branch: Mechanical Engineering
THEORY OF MACHINES-I
2002 admission onwards
Regular/Supplementary
Time: Three Hours Maximum 100Marks
Answer all questions
PartA
1.State and prove Kennedys theorem.
2.Differentiate between a mechanism and a machine.
3.Briefly explain the number synthesis.
4.What are the features of kinematics synthesis?
5.With a neat sketch, explain the Scott-Russell mechanism
6.Briefly explain the working of a Pantograph.
7.Write a note on classification of brakes.
8.What is meant by torsion dynamometer? Explain.
9.What is the condition for constant velocity ratio in gears? Explain.
10.Define (i)Arc of contact;(ii)Path of contact; and (iii)Contact ratio.
(10x4=40)
Part B
11.With the help of neat sketches, explain any three mechanisms, which are the inversion of a single slider crank chain used in engineering proactive
Or
12.The crank and slotted lever has the maximum stroke length of 300 mm Maximum velocity ratio is 2.Determine (i)Length of slotted lever;(ii)Ratio of times of cutting and return stroke
Or
13. (a)Explain the overlay method of kinematics synthesis
(b)What are the graphic methods of dimensional synthesis?
14.Explain the procedure to obtain the chebyshev spacing for three precision points given y=x.8 for the range 1<x<3
Or
15.Derive a condition to generate a straight-line mechanism. Prove that Peacullier mechanism satisfies the condition.
Or
16.Describe with neat sketch, a quick return mechanism for a shaping machine.
17.With neat sketches Explain:
(a) Single plate clutch
(b) Hydraulic Power brake
(c) Torsion dynamometer
Or
18.A multi disk clutch consists of steel and bronze plates. It transmits 15 kW at 1400 r.p.m. The inner and outer diameters of containing surfaces are 100 mm and 200 mm respectively. The coefficient of friction is .15 and the permissible intensity of pressure is .5N/mm2. Calculate the number of steel and bronze disks.
19.What do you understand by Interference as applied to gears? Derive an expression for minimum number of teeth required on the pinion in order to avoid interference in gear teeth
Or
20. (a)Derive an expression for efficiency of worm gears.
(b)Write a note on standard and non standard gear tooth properties
Answer Key
1.The Kennedys theorem states that if three bodies move relative to each other, they have three instantaneous centers and lie on a straight line.
Refer text book by R.S khurmi. Page No.114
2.Machine
1.It is like a human body used for transmitting energy in to useful work
2.It is the practical development of machine.
3.It is related to the energy.
4.It has many links
Eg.Lathe, Shaper etc
Mechanism
It is like skeleton and has definite motion between the various links. It is the model of a machine. It is related to the motion onlyEg. Engine indicator, Type writer etc
3.The synthesis of the mechanism is the design or creation of a mechanism to produce a desired output motion for a given input motion. It deals with the determination of proportions of a mechanism for the given input and out put motion. In the application of synthesis, to the design of a mechanism the problem divides itself in to the following 3 parts
1.Type synthesis
2.Number synthesis
3.Dimensional synthesis
Number synthesis deals with the number of links and the number of joints needed to produce the required motion
4.The synthesis of the mechanism is the design or creation of a mechanism to produce a desired output motion for a given input motion. It deals with the determination of proportions of a mechanism for the given input and out put motion. In the application of synthesis, to the design of a mechanism the problem divides itself in to the following 3 parts
1.Type synthesis
2.Number synthesis
3.Dimensional synthesis
Number synthesis deals with the number of links and the number of joints needed to produce the required motion
5Refer Text book by V.P.Singh Page No:230
6.Pantograph is an instrument used to produce the drawings in to different scales. It is used to trace the path to an enlarged scale or reduced scale.
Refer Text book by V.P.Singh Page No: 233
7.Block or shoe brake
It consists of a shoe pressed against a rotating wheel. Force on the drum is applied through a lever. The system may consist of single or double shoes. The side thrust in single shoe brake can overcome by Double shoe
Band brake
It consists of a rope, belt or flexible band lined with friction material, covering the external surface of a brake drum and controlled by a lever for applying the brakes. When the force is applied at the free end of the lever, the band ids pressed against the surface of the drum. The friction material retards the motion.
Band and Block brake
It is the modification of the band brake. and consists of a number of wooden blocks fixed inside a flexible steel band. The friction between the blocks and drum provides the braking action
Refer Text book by R.K.Bansal Page No:331
8.It is used for measuring large powers. When the power is being transmitted, then the driving end of the shaft twists through a small angle relative to the driven end of the shaft. The amount of twist depends on factors such as torque acting on the shaft (T0, length of the shaft (L), diameter of the shaft (d),modulus of rigidity(c),the material of the shaft etc
The torsion eqn is T/J=Cθ/L
9.The common normal to the two surfaces at the point of contact intersects the line joining the centers of rotation of the two surfaces at a fixed point, which divides the center distance inversely as the ratio of angular velocities.
Refer Text book by R.K.Bansal Page No:402
10.Path of contact
It is the curve traced by the point of contact of the two mating teeth from the beginning to the end of the two teeth.
Arc of contact
It is the path traced by a point on the pitch circle from the beginning to the end of engagement of a pair of teeth
Contact ratio
It is the ratio of length of arc of contact to the circular pitch.
Part B
11.Inversion of slider crank chain
(a)Pendulum pump.
Fixing the sliding link of a reciprocating steam engine makes it
(b)Crank and slotted lever mechanism
(C)Whitworth Quick return Motion
Refer Text book by V.P.Singh Page No. 10
13. (a)Refer Text book by V.P.Singh Page No. 212
(b)Two position synthesis of four bar mechanism
Two position synthesis of slider crank mechanism
Three position synthesis of four bar mechanism
Three position synthesis of slider crank mechanism
14. x0=1,xn+1=3
a = (xn+1 + x0)/2
b=(1/2)(xn+1 - x0)
xj =( a b) cosθjx3.14
15.Reffer Text book by V.P.Singh Page No. 232
16.Reffer Text book by V.P.Singh Page No. 9
17.Reffer Text book by V.P.Singh Page No. 158
18. r2 = 100mm,r1=200mm,N = 1400 rpm, w= (2x3.14x1400)/60,P =15KW,p=.5N/mm2
Load is given by
W = 2x3.14xr2(r1-r2)
Torque transmitted
T1 = (1/2)x.15xWX(r1+r2)
Total torque transmitted
P = T2 w
T 2= P/w
So number of friction surfaces required
=T1/T2
19.Interference is the phenomenon between the two mating teeth when the tip of one tooth undercuts the root of other mating tooth.
Minimum No. of teeth on the pinion in order to avoid interference= (2Ap)/(1+G(G+2)Sin2 )1/2-1
Refer textbook by R.K.Bansal Page No.424
20.Refer textbook by R.K.Bansal Page No.436
B.TECH DEGREE EXAMINATION, MAY 2008
First year
Branch: Electronics and Communication Engineering
BASIC MECHANICAL ENGINEERING
Regular/Supplementary
Time: Three Hours Maximum: 100Marks
Answer all questions
Part A
1.Diffenentiate closed system and open system. Give examples.
2.Calculate characteristic gas constant for oxygen.
3.What are the functions of piston crown in two-stroke petrol engine?
4.Explain the term ton of refrigeration.
5.In power transmission systems where were belts and gears are used?
6.What do you mean by 7x 10 ropes? What are the materials used for making ropes?
7.What are the pollutants from Nuclear power plant?
8.What do you understand by specific speed of hydraulic turbine?
10.What is rolling? With a neat sketch, explain three roll mill.
(10x4=40 marks)
Part B
11. (a)What is intensive property and extensive properties? From the following properties differentiate intensive and extensive properties
(i) Volume (ii) Kinetic energy (iii) Specific enthalpy (iv) Internal energy (v) Density (vi) Temperature (vii) Flow work (viii) Pressure
Or
(b) 1 kg of gas expands adiabatic ally and its temp. is observed to fall from 240 c to 115 c while the vol. Is doublwed.The gas does 90 kJ of work during the process .Determine The value of Cp and Cv.
12. (a)Explain the working principle of a four stroke diesel engine with neat sketch.
Or
(b) With a neat sketch, explain vapor compression refrigeration system.
13. (a)What are the different types of gears used in power transmission systems? Explain the situations where they used.
Or
(b) An open belt drive transmits power of 42 kW with a velocity of 7m/sec. Find the tensions on each side of the belt. if μ=0.25 and angle of lap is 170
14 (a) With a neat sketch explain Nuclear power plant.
Or
(b) Compare hydroelectric and steam power plants.
15(a) Explain the following (i) slab milling (ii) Face milling (iii) Form milling (iv) End milling (v) T-slot milling
Or
(b) Describe a milling machine with a neat sketch
ANSWER KEY
1. Closed system the system does not permit the transfer of mass across the boundary and permits the transfer of energy.
|
Cylinder
Piston
|
Movable boundary
|
Fixed boundary
The boundary of a closed system may or may not change position
Open system
the system, which allows the transfer of mass and energy across the boundary.
Turbines and pumps are examples.
Mass out
|
|
|
||||
|
||||||
Steam turbine
Work
|
|||
|
|||
Mass in
2. Refer text book by J.Benjamin,Page No.1.17
3. Refer text book by J.Benjamin,Page No.2.5
4. Unit of Refrigeration:-
the rate of heat absorbed by the refrgn system from the
body to be cooled, equivalent to the latent heat of fusion of
one ton of ice from and at 00C in 24 hrs is called one ton of
refrgn. The STD unit of refrgn is ton of refrgn or ton
5. BELT DRIVE: - This type of drive is used when the power is to be transmitted from one shaft to other which are at a distance. Pulleys are mounted on the driver and driven/follower shafts and an endless belt is fitted tightly over these pulleys. The frictional resistance between these pulleys and belt is the reason for the power transmission, which depends on the velocity of belt, tension of the belt and arc of contact of the belt in the smaller pulley. There are flat belt and V- belt used for the power transmission.
GEAR DRIVES: -Toothed wheel is the gear for transmitting power between two shafts, which are very closer. The teeth of the gear mounted on the shaft meshes each other during rotation. Gears are manufactured either by milling, by casting or by hobbing. Spur gear, helical gear, bevel gear, worm gear are different types.
6. Refer text book by J.Benjamin,Page No.3.5.
7. Refer text book by J.Benjamin,Page No.4.15
8.It is the speed of the turbine , when it produces unit power when
working under unit head.
10.Refer text book by J.Benjamin,Page No.5.37
11.(a) Intensive and extensive property if the value of a property is independent of mass of the system then it is called intensive property. When the whole or part of the system is considered, if the value of the property remains the same it is again intensive property. If the value of the property is proportional to the mass of the system, it is called extensive property. Vol, energy. are examples
(b)Refer text book by J.Benjamin,Page No.1.46
12.(a) Refer text book by J.Benjamin,Page No.2.8
(b) Vapor compression system:- in this system the working fluid is readily evaporates and condenses. It evaporates absorbing heat from the space and rejects heat to the surroundings during condensing. The following are the basic components of a simple vapor compression system.
5. compressor
6. condenser
7. expansion valve
8. evaporator cooling
Water
|
||||
|
||||
3
|
|
||||
|
|||||
2 1
3 2
2
pr
4
Evaporator
1
|
|
4
|
|||||
|
|||||
|
|||||
H brine solution
-10-
the line diagram of the system and its pr-enthalpy plotting is shown in the fig. The dry saturated vapor of the working fluid (Freon or R12) is entered in to the compressor at pr p1 and temp T1during its suction stroke and compressed isentropically to pr p2 and temp T2. The line 1-2 in the p-H diagram shows this process.
At the end of the compression, the high temp and high pr vapor is in the super heated state passes to the condenser through which water is circulated to receive heat from the vapor. The vapor is cooled to the saturation temp at 2 and at constant pr. The cooling continues till the vapor reached at 3 in the liquid phase at low temp and high pr. The latent heat of condensation removes from the vapor by this time. This high pr low temp liquid is allowed to expand by passing through an expansion valve. Now the pr and temp very low to p1. The expansion process 3-4 is a const enthalpy process. During throttling the liquid partly evaporates and gets a liquid vapor mixture at temp T1 and pr p1.
This vapor passes through the evaporator coil, which is surrounded by the items/liquid (brine solution) to be cooled. The refrigerant from the expansion valve will absorb heat of the brine solution in the evaporator and gets vaporized and reaches the dry saturated condition at 1and thus completing one cycle of operation.
The cold brine then circulated through coils around the space to be refrigerated. The net refrigerating effect of the system is heat absorbed by the refrigerant from the brine. The work done by the compressor is the heat added to the refrigerant during the compression process
Heat extracted from the brine
COP = --------------------------------------
Work done by the compressor
13.(a)Refer text book by J.Benjamin,Page No.3.7
(b) Refer text book by J.Benjamin,Page No.3.15
14.(a)Refer text book by J.Benjamin,Page No4.14
(b) Refer text book by J.Benjamin,Page No 4.11
15.(a)Refer text book by J.Benjamin,Page No5.19
(b) Refer text book by J.Benjamin,Page No5.14
| Earning: Approval pending. |
