# Mechanical Engineering (Test 4)

## Upsc Civil Services Entrance Exams : Civil Services Aptitude Test (csat)

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Mechanical Engineering
| Engineering Mathematics | | Applied Mechanics and Design | | Fluid Mechanics and Thermal Sciences | | Materials, Manufacturing and Industrial Engineering |
Q.1
A minimal spanning tree in network flow models involves
A. All the nodes with cycle/loop allowed
B. All the nodes with cycle/loop not allowed
C. Shortest path between start and end nodes
D. All the nodes with directed arcs
Explaination / Solution:

A path forms a loop or cycle if it connects a node itself. A spanning tree links all the nodes of network with no loops allowed.

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Q.2
The word kanban is most appropriately associated with
A. Economic order quantity
B. Just–in–time production
C. Capacity planning
D. Product design
Explaination / Solution:
No Explaination.

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Q.3
The crystal structure of aluminium is
A. body-centred cubic
B. face-centred cubic
C. close-packed hexagonal
D. body-centred tetragonal
Explaination / Solution:
No Explaination.

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Q.4
Match the following products with preferred manufacturing processes:
Product                                  Process
P Rails                                   (1)Blow molding
Q Engine crankshaft              (2) Extrusion
R Aluminium channels           (3) Forging
S PET water bottles               (4) Rolling
A. P - 4, Q - 3, R - 1, S - 2
B. P - 4, Q - 3, R - 2, S - 1
C. P - 2, Q - 4, R - 3, S - 1
D. P - 3, Q - 4, R - 2, S - 1
Explaination / Solution:
No Explaination.

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Q.5
Match the following metal forming processes with their associated stresses in the work-piece.
Metal forming process             Type of stress
1. Coining                                P. Tensile
2. Wire Drawing                      Q. Shear
3. Blanking                              R. Tensile and compressive
4. Deep Drawing                     S. Compressive
A. 1-S, 2-P, 3-Q, 4-R
B. 1-S, 2-P, 3-R, 4-Q
C. 1-P, 2-Q, 3-S, 4-R
D. 1-P, 2-R, 3-Q, 4-S
Explaination / Solution:

Coining → Compressive
Wire drawing→ Tensile
Blanking → Shear
Deep Drawing → Tensile and Compressive

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Q.6
Two cutting tools are being compared for a machining operation. The tool life equations are:
Carbide tool:  VT1.6 = 3000
HSS tool:        VT0.6 = 200
Where V is the cutting speed in m/min and T is the tool life in min. The carbide toll will provide higher tool life if the cutting speed in m/min exceeds
A. 15.0
B. 39.4
C. 49.3
D. 60.0
Explaination / Solution:
No Explaination.

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Q.7
Electrochemical machining is performed to remove material from an iron surface of 20mm × 20mm under the following conditions:
Inter electrode gap= 0.2mm
Supply voltage (DC)= 12V
Specific resistance of electrolyte = 2Ωcm
Atomic weight of Iron= 55.85
Valency of Iron = 2
The material removal rate (in g/s) is
A. 0.3471
B. 3.471
C. 34.71
D. 347.1
Explaination / Solution:
No Explaination.

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Q.8
For tool A, Taylor’s tool life exponent (n) is 0.45 and constant (K) is 90. Similarly for tool B, n=0.3 and K=60. The cutting speed (in m/min) above which tool A will have a higher tool life than tool B is
A. 26.7
B. 42.5
C. 80.7
D. 142.9
Explaination / Solution:
No Explaination.

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Q.9
The pressure, dry bulb temperature, and relative humidity of air in a room are1bar, 30ºC and 70% respectively. If the saturated steam pressure at 30ºC is 4.25kPa, the specific humidity of the room air in kg water vapour / kg dry air is
A. 0.0083
B. 0.0101
C. 0.0191
D. 0.0232
Explaination / Solution:

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Q.10
If a mass of moist air in an airtight vessel is heated to a higher temperature, then
A. Specific humidity of the air increases
B. Specific humidity of the air decreases
C. Relative humidity of the air increases
D. Relative humidity of the air decreases