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The resistances of each branches KL, LM, MN, NK is R and that of LN is 1.414 R. the equivalent resistance between K and M is<br><img src="/images/question-image/mining-engineering/mine-ventilation/1682422776-M2-3-88-109.PNG" title="Mine Ventilation mcq question image" alt="Mine Ventilation mcq question image">
A
R
B
0.5 R
C
0.75 R
D
2 R
Correct Answer:
0.5 R
A mine ventilation system consists of two splits A and B with resistances of 0.8 Ns
2
m
-8
and 3.2 Ns
2
m
-8
, respectively as shown in figure. Trunk airways have resistance of 0.2 Ns
2
m
-8
. The main mine fan is generating pressure of 500 Pa.
The air quantities in m
3
/s circulated in the splits A and B respectively are
A
20 and 30
B
30 and 20
C
20 and 10
D
40 and 10
A mine ventilation system consists of two splits A and B with resistances of 0.8 Ns
2
m
-8
and 3.2 Ns
2
m
-8
, respectively as shown in figure. Trunk airways have resistance of 0.2 Ns
2
m
-8
. The main mine fan is generating pressure of 500 Pa.
The flows in the two splits are equalized by placing a booster fan in split B. Assume that the fan pressure does not change after installation of the booster fan. The size of the booster fan in Pa is
A
749.05
B
850.08
C
950.02
D
1000.5
The main fan operating point of a ventilation system is shown in the figure below. If an NPV of 200 Pa assists the ventilation system, the resultant pressure (Pa) and quantity (m
3
) generated by the
A
500, 681
B
600, 63
C
640, 55
D
400, 63
E
640, 66
Two splits A and B are ventilated from an intake airway. Resistances of the splits are 0.5 Ns
2
m
-8
and 0.8 Ns
2
m
-8
respectively. A regulator is placed in split B to maintain a flow of 15 m
3
/s and 10 m
3
/s in splits A and B respectively as shown in the figure. The size of the regulator in m
2
is
A
2.1
B
1.3
C
1.2
D
1.13
The figure shows PV (pressure-volume) diagram of a mine ventilated by both natural means and an exhaust fan. The total ventilation energy is represented by
A
Area ABF + Area CDEF
B
Area ABRS + Area CDEF
C
Area ABRS + Area QDCR
D
Area ABF + Area QDCR
While measuring average air velocity of air flowing through a circular duct using precise traversing with equal area method, the radii r
1
, r
2
and r
3
, in mm, as shown in the figure of the three circles should be
A
83, 167 and 240
B
36, 107 and 261
C
102, 177 and 228
D
108, 157 and 216
Statements :
All branches are flowers. All flowers are leaves.
Conclusions :
I. All branches are leaves.
II. All leaves are branches.
III. All flowers are branches.
IV. Some leaves are branches.
A
None follows
B
Only I and IV follow
C
Only II and III follow
D
All follow
E
All follow
In a mine ventilation system, the resistances of two splits A and B are 0.5 Ns
2
m
-8
and 2 Ns
2
m
-8
respectively. Combined resistance of two shafts and trunk airways is 0.7 Ns
2
m
-8
. A quantity of 20 m
3
/s of air passes through split A. The total air power of the ventilation system in kW are
A
82.9
B
48.9
C
24.9
D
27.9
A network administrator is connecting hosts A and B directly through their Ethernet interfaces, as shown in the illustration. Ping attempts between the hosts are unsuccessful. What can be done to provide connectivity between the hosts?
1. A crossover cable should be used in place of the straight-through cable.
2. A rollover cable should be used in place of the straight-through cable.
3. The subnet masks should be set to 255.255.255.192.
4. A default gateway needs to be set on each host.
5. The subnet masks should be set to 255.255.255.0.
A
1 only
B
2 only
C
3 and 4 only
D
1 and 5 only
E
2 and 5 only
In the circuit given below, what is the current flowing in 6Ω resistances?
A
0.22
B
0.55 A
C
2.22 A
D
2.775 A
