Exam Details
| Subject | mechanical engineering | |
| Paper | paper 1 | |
| Exam / Course | indian forest service | |
| Department | ||
| Organization | union public service commission | |
| Position | ||
| Exam Date | 2003 | |
| City, State | central government, |
Question Paper
MECHANICAL ENGINEERING
PAPER I
SECTION A
I . Answer any four of the following:
(Each answer should conform to a limit of around 150 words)
Distinguish between the laws of friction or dry and film lubricated sun·aces.
What conditions must be satisfied in order that film lubrication may be obtained.
Explain the difference between oiliness and viscosity of a lubricant.
Discuss the condition under which friction between two lubricated surfaces is
influenced by the two properties respectively
Explain briefly the role of factors that influence, the change in the sum of tensions on the slack and tight side of a bell transmission, as power transmitted is increased.Why is a horizontal drive capable of transmitting more power than a similar vertical drive'?
Explain clearly the meanings of terms elastic solid, monelastic solid, inelastic solid, linearly elastic solid. and nonlinearly elastic solid. Illustrate your answer using a diagram showing the load-deformation relationship for the above solids
Define allotropy Give an example of different allotropic forms of a material.
What is edge dislocation?
Prove that the atomic paC!king factor of a liOP (Hexagonally Close-Packed) structure
is 0.74
(i)What are solubility limits?
(ii)Describe an eutectic structure.
(iii)Why does the cooling Curve for a pre metal show a isothermal hold at the freezing
(i)Explain briefly why the static deflection curve of a loaded shaft may be used as a whirling form
(ii)Establish the relationship of critical speed with loads and load point deflections
A shaft Y is driven by a coaxial shaft X through the epicyclic gear train as shown in the above figure. The wheel A is keyed to and E to Y. The compound wheel BD is carried on the arm F which can rotate freely about the common axis of X and Y.the wheel C is fixed. The number of teeth on the gears and E arc respectively 20,64,80,30 and 50.The shaft X rotates at 600 rmp clockwise looking from A.Determine the speed (in RPM} of Y and the direction of rotation,looking from E.(25)
A beam bas a cross section in the form of an isosceles triangle of base b and height h. derive
an expression for the magnitude of the minimum Horizontal shearing stress under a vertical
shear force V. What will be lire location of this stress?
If the beam has b 10cm. and h 30cm, find the magnitude of maximum sheer stress, and
the shear stress at neutral axis when V 10,000 Kgf.
Two springs, outside diameters 45 mm and 65 mm respectively are made with a steel wire of
diameter 5 mm, and are placed coaxially, Both the springs have 25 active coils but the outer
spring is 27 mm longer than the inner one.
Find the compression of the inner spring when a load of 15 Kgf is placed on a plate supported initally
by the inner spring
G for spring wire 8 x 10 5 Kgf/cm2
State the theories of failure based on the following criteria:
Maximum Stress
Maximum Shear Stress
Maximum Strain Energy
Maximum Distortion Energy
Compare the safe stress domains based on the above criteria illustring your answer with sigma1,
sigma safe domain plot for a two dimensional stress state. Compare the safe values based on
each of the above theories for the specific case sigma1 -sigma2.
Determine the width of 9.5 mm thick leather belt required to transmit 10 KW from a motor running at 750 rpm. The motor pully is 300 mm diameter. The driven pully runs at 250 rpm and the centre distance between the pulleys is 3 m.
Assume an open belt drive with no slip and Relative Density 0f Lether 1.0.
Maximum permissible Stress for leather bell 264 N/mm2 Friction between belt and pullcy 0.3. Neglect the sag of belt and the effect of thickness of belt on velocity
SECTION B
5. Answer any four of the following: (Ech answer should conform to a limit of around (150 words)
Explain the difference between tolerance and allowance.
D1scuss the terms roughness· weaviness and lay·
Why is springback important in cold forming?
Why most press forging oil employ heated dies?
What is concept related In jig and fixture design
What are various types of value? What do you personally gain From value engineering?
Give some example of waiting time situations existing in industry.
Draw figure shwing four waiting line structures.
What type of distributions are assumed for arrivals and services?
In a single channel waiting line if new gama what will be the utilization factor and mean waiting time for a customer before being served new Av· no, of services provided per unit time and y Av. no of arrivals per unit time. 3.q)
fel 1 Wri r·e lite 11urpvsc 11f in n comput.::r propram including it$ gencrnl fom1
til 1 Nnme types or plot ret'S used in computer; to produce loard copy.
tn) Wmc the ClfOIItl$ wlliOh mnkc COillrol iOOJlllllll Ill machine.
Whnr is meam by the following codes'/
Ul 0 3
tb) DC servomotor is coupled directly ro a lead screw which drives the table of an NC machine
lool. A digflal encoder. winch emirs 500 pulses per revolution is motmtcd on the or her end of
lead screw. lfrbe dead screw pitch is 5mrn and motor rorates at 800 rpm, calculate.
1 The linear vcloctry of 1l1e ruble
1 ii)Thc llask nml tBLU) of the N.C. system
TIIC froquUOC) oflhe 1fi111Sn1111Cd hy the I I Bl ll.
1151
tel Explnm with a stylus profile tlevice fcJr m.msunng Sllrfiocc
ii l How Ra (arnhmettc mean) value smfirce roug.hness ts delined7
I l Sl
Florence He31tb INC ts a Professional IT nursmg borne aspiring to become Professional
nursing home. Administ.rntor prepares dte following list ofnctivines:
Oraw the PERT dUIJ::fliDI and d te ctirical padt (eonstder P·disuiburion). Vllm is
l·fme/Cost trade
Solve the assignment problem represenred by rbe matri..._ given below:
• b d l
II lJ 27
B 12 50 6S 48
c 28 91 !17 45 3:J
0 711 42 21 40 39
E ao 11 67 22 26
p s GS 31 17 1!8
8.
4 or&
Discuss the prlnciple and applications of slip gauges. What are the different grades of
accuracy?
Draw Merchams circular force diagram and write the assumplions.
Solve the following linear J>rogr.utuniug problem
Maximize
z 3x1 2x2 5x3
Subject to
2x", 5 430
Zx, 5 460
420
s x. s 0
2.
PAPER I
SECTION A
I . Answer any four of the following:
(Each answer should conform to a limit of around 150 words)
Distinguish between the laws of friction or dry and film lubricated sun·aces.
What conditions must be satisfied in order that film lubrication may be obtained.
Explain the difference between oiliness and viscosity of a lubricant.
Discuss the condition under which friction between two lubricated surfaces is
influenced by the two properties respectively
Explain briefly the role of factors that influence, the change in the sum of tensions on the slack and tight side of a bell transmission, as power transmitted is increased.Why is a horizontal drive capable of transmitting more power than a similar vertical drive'?
Explain clearly the meanings of terms elastic solid, monelastic solid, inelastic solid, linearly elastic solid. and nonlinearly elastic solid. Illustrate your answer using a diagram showing the load-deformation relationship for the above solids
Define allotropy Give an example of different allotropic forms of a material.
What is edge dislocation?
Prove that the atomic paC!king factor of a liOP (Hexagonally Close-Packed) structure
is 0.74
(i)What are solubility limits?
(ii)Describe an eutectic structure.
(iii)Why does the cooling Curve for a pre metal show a isothermal hold at the freezing
(i)Explain briefly why the static deflection curve of a loaded shaft may be used as a whirling form
(ii)Establish the relationship of critical speed with loads and load point deflections
A shaft Y is driven by a coaxial shaft X through the epicyclic gear train as shown in the above figure. The wheel A is keyed to and E to Y. The compound wheel BD is carried on the arm F which can rotate freely about the common axis of X and Y.the wheel C is fixed. The number of teeth on the gears and E arc respectively 20,64,80,30 and 50.The shaft X rotates at 600 rmp clockwise looking from A.Determine the speed (in RPM} of Y and the direction of rotation,looking from E.(25)
A beam bas a cross section in the form of an isosceles triangle of base b and height h. derive
an expression for the magnitude of the minimum Horizontal shearing stress under a vertical
shear force V. What will be lire location of this stress?
If the beam has b 10cm. and h 30cm, find the magnitude of maximum sheer stress, and
the shear stress at neutral axis when V 10,000 Kgf.
Two springs, outside diameters 45 mm and 65 mm respectively are made with a steel wire of
diameter 5 mm, and are placed coaxially, Both the springs have 25 active coils but the outer
spring is 27 mm longer than the inner one.
Find the compression of the inner spring when a load of 15 Kgf is placed on a plate supported initally
by the inner spring
G for spring wire 8 x 10 5 Kgf/cm2
State the theories of failure based on the following criteria:
Maximum Stress
Maximum Shear Stress
Maximum Strain Energy
Maximum Distortion Energy
Compare the safe stress domains based on the above criteria illustring your answer with sigma1,
sigma safe domain plot for a two dimensional stress state. Compare the safe values based on
each of the above theories for the specific case sigma1 -sigma2.
Determine the width of 9.5 mm thick leather belt required to transmit 10 KW from a motor running at 750 rpm. The motor pully is 300 mm diameter. The driven pully runs at 250 rpm and the centre distance between the pulleys is 3 m.
Assume an open belt drive with no slip and Relative Density 0f Lether 1.0.
Maximum permissible Stress for leather bell 264 N/mm2 Friction between belt and pullcy 0.3. Neglect the sag of belt and the effect of thickness of belt on velocity
SECTION B
5. Answer any four of the following: (Ech answer should conform to a limit of around (150 words)
Explain the difference between tolerance and allowance.
D1scuss the terms roughness· weaviness and lay·
Why is springback important in cold forming?
Why most press forging oil employ heated dies?
What is concept related In jig and fixture design
What are various types of value? What do you personally gain From value engineering?
Give some example of waiting time situations existing in industry.
Draw figure shwing four waiting line structures.
What type of distributions are assumed for arrivals and services?
In a single channel waiting line if new gama what will be the utilization factor and mean waiting time for a customer before being served new Av· no, of services provided per unit time and y Av. no of arrivals per unit time. 3.q)
fel 1 Wri r·e lite 11urpvsc 11f in n comput.::r propram including it$ gencrnl fom1
til 1 Nnme types or plot ret'S used in computer; to produce loard copy.
tn) Wmc the ClfOIItl$ wlliOh mnkc COillrol iOOJlllllll Ill machine.
Whnr is meam by the following codes'/
Ul 0 3
tb) DC servomotor is coupled directly ro a lead screw which drives the table of an NC machine
lool. A digflal encoder. winch emirs 500 pulses per revolution is motmtcd on the or her end of
lead screw. lfrbe dead screw pitch is 5mrn and motor rorates at 800 rpm, calculate.
1 The linear vcloctry of 1l1e ruble
1 ii)Thc llask nml tBLU) of the N.C. system
TIIC froquUOC) oflhe 1fi111Sn1111Cd hy the I I Bl ll.
1151
tel Explnm with a stylus profile tlevice fcJr m.msunng Sllrfiocc
ii l How Ra (arnhmettc mean) value smfirce roug.hness ts delined7
I l Sl
Florence He31tb INC ts a Professional IT nursmg borne aspiring to become Professional
nursing home. Administ.rntor prepares dte following list ofnctivines:
Oraw the PERT dUIJ::fliDI and d te ctirical padt (eonstder P·disuiburion). Vllm is
l·fme/Cost trade
Solve the assignment problem represenred by rbe matri..._ given below:
• b d l
II lJ 27
B 12 50 6S 48
c 28 91 !17 45 3:J
0 711 42 21 40 39
E ao 11 67 22 26
p s GS 31 17 1!8
8.
4 or&
Discuss the prlnciple and applications of slip gauges. What are the different grades of
accuracy?
Draw Merchams circular force diagram and write the assumplions.
Solve the following linear J>rogr.utuniug problem
Maximize
z 3x1 2x2 5x3
Subject to
2x", 5 430
Zx, 5 460
420
s x. s 0
2.