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A mine airway having cross-section of 2.2 m × 2.2 m and length 500 m contains a bend. Given that the airway friction factor is 0.01 Ns<sup>2</sup>m<sup>-4</sup>, shock loss factor for the bend is 0.07 and density of air is 1.2 kg/m<sup>3</sup>, the equivalent length of the airway in m is
A
502.31
B
622.51
C
534.51
D
512.31
Correct Answer:
502.31
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
A pumping station in a mine has 4 pumps, P
1
, P
2
, P
3
and P
4
which are connected functionally in parallel configuration as shown in the figure. The individual reliability of the pumps P
1
, P
2
, P
3
and P
4
are 0.80, 0.90, 0.85 and 0.95 respectively. For an effective dewatering operation in the mine denoting system success, at least three pumps should be in operation. The reliability of the system is
A
0.19
B
0.93
C
0.99
D
0.58
A main fan of a mine circulates 40 m
3
/s of air at a pressure of 500 Pa. the mine has two splits of equal resistance. The trunk airways have a total resistance of 0.2 Ns
2
/m
8
. When a booster fan is installed in one split, the flow of air in the other splits stops. Assuming that the pressure remains unchanged, the new air quantity flowing through the mine in m
3
/s is
A
20
B
30
C
40
D
50
Seven people A, B, C, D, E, F and G live on separate floors of a 7-floor building. Ground floor is numbered 1, first floor is numbered. 2 and so on until the topmost floor is numbered 7. Each one of these having a different cars-Cadillac, Ambassador, Fiat, Maruti, Mercedes, Bedford and Fargo but not necessarily in the same order. Only three people live above the floor on which A lives. Only one person lives between A and the one having a car Cadillac. F lives immediately below the one having a car Bedford. The one having a car Bedford lives on an even-numbered floor. Only three people live between the ones having a car Cadillac and Maruti. E lives immediately above C. E is not having a car Maruti. Only two people live between B and the one having a car Fargo. The one having a car Fargo lives below the floor on which B lives. The one having a car Fiat does not live immediately above D or immediately below B. D does not live immediately above or immediately below A. G does not have a car Ambassador. Question : How many people live between the floors on which D and the one having a car Bedford ?
A
One
B
Two
C
Three
D
Four
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
A mine airway 2m wide, 2.5m high and 500m long. The airway passes a quantity of 8m
3
per second. Calculate its pressure loss? Assume k = 0.0098 NS
2
m
-4
A
11 Pa
B
21 Pa
C
31 Pa
D
50 Pa
Pressure characteristic of a mine fan is given by. P = -0.06Q
2
+ 400. where P is the pressure in Pa and Q is the quantity in m
3
/s. The resistance of the mine is 0.19 Ns
2
/m
8
. An identical fan is installed in the mine to operate in series with the existing fan. The new mine quantity in m
3
/s is
A
75.6
B
56.7
C
50.8
D
30.2
Air at a density of 1.2 kg/m
3
flows in a straight duct such that the velocity at the centre is 12.5 m/s. the method factor for the velocity profile is known to be 0.80. The air flow encounters a symmetric expansion such that the cross- sectional are of the duct becomes double. The static pressure value at the inlet and outlet of the expansion are 60 Pa and 90 Pa respectively. Neglecting friction the shock pressure loss on account of expansion in Pa is
A
15
B
22
C
38
D
46
A shaft is subjected to fluctuating loads for which the normal torque (T) and bending moment (M) are 1000 N-m and 500 N-m respectively. If the combined shock and fatigue factor for bending is 1.5 and combined shock and fatigue factor for torsion is 2, then the equivalent twisting moment for the shaft is
A
2000 N-m
B
2050 N-m
C
2100 N-m
D
2136 N-m
