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Air at a density of 1.2 kg/m<sup>3</sup> 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
Correct Answer:
15
Air at a density of 1.2 kg/m
3
flows in a straight duct such that the velocity at the centre is 12.5m/s. the method factor for the velocity profile is known to be 0.80. The velocity pressure value in the duct in Pa is
A
31
B
47
C
60
D
83
Air at atmospheric pressure and 20 degree Celsius flows with 6 m/s velocity through main trunck duct of air conditioning system. The duct is rectangular in cross-section and measures 40 cm by 80 cm. Determine heat loss per meter length of duct corresponding to unit temperature difference. The relevant thermos-physical properties of air are v = 15 * 10 -6 m 2/s α = 7.7 * 10 -2 m2/hr k = 0.026 W/m degree
A
32.768 W
B
42.768 W
C
52.768 W
D
62.768 W
An exhaust fan attached to an evasee of 18 m
2
cross-sectional area at the outlet circulates 150 m
3
/s of air at the pressure of 1000 Pa in a mine ventilation system. The ratio of the inlet to outlet area of the evasee is 1 : 4 and the density of air is 1.2 kg/m
3
. The quantity of air circulated in the mine in absence of evasee is 120 m
3
/s. The eva see efficiency in % is
A
57.6
B
43.2
C
39.06
D
37.7
A tank has an inlet and outlet pipe. The inlet pipe fills the tank completely in 2 hours when the outlet pipe is plugged. The outlet pipe empties the tank completely in 6 hours when the inlet pipe is pluggeed. If there is a lekage also which is capable of draining out the liquid from the tank at half of the rate of outet pipe,them what is the time taken to fill the emty tank when both the pipes are opened?
A
3 hours
B
4 hours
C
5 hours
D
None of these
The lubricating oil for a large industrial gas turbine engine is cooled in a counter flow, concentric tube heat exchanger. The cooling water flows through the inner tube ( diameter = 25 mm) with inlet temperature 25 degree celsius and mass flow rate 0.2 kg/s. The oil flows through the annulus (diameter = 50 mm) with mass flow rate 0.125 kg/s and its temperature at entry and exit are 90 degree Celsius and 60 degree Celsius. Find outlet temperature of cooling water
A
14.58 degree celsius
B
24.58 degree celsius
C
34.58 degree celsius
D
44.58 degree celsius
A pitot tube is inserted in a ventilation duct with the nose facing the air flow. A vertical U-tube manometer filled with alcohol (specific gravity 0.8) has been used for pressure measurements such that 10.2 mm is read as the total pressure and 8.8 mm as the static pressure. Given the density of air to be 1.2 kg/m
3
, the air velocity at the nose of the pitot tube in m/s is
A
4.27
B
6.53
C
3.29
D
5.67
Two outlets of a motor manufacturing company reported that revenue from outlet x in 2013 was down 11 percent from 2012. and revenue from outlet Y in 2013 were up 7 percent from 2012. If total revenue from outlet X & Y in 2013 was up 1 percent from 2012, what is the ratio of revenue from outlet X in 2012 revenue from outlet Y in 2012?
A
1 : 2
B
4: 5
C
1 : 1
D
3: 2
Air flows at 2 m
3
/s through a forcing fan duct of 0.3 m
2
having uniform cross-section. The duct resistance is 40 Ns
2
m
-8
and air density is 1.2 kg/m
3
. The total pressure generated by the fan in Pa is
A
186.7
B
160.0
C
133.3
D
26.7
Which of the following statements regarding static methods are correct?
1. Static methods are difficult to maintain, because you can not change their implementation.
2. Static methods can be called using an object reference to an object of the class in which this method is defined.
3. Static methods are always public, because they are defined at class-level.
4. Static methods do not have direct access to non-static methods which are defined inside the same class.
A
1 and 2
B
2 and 4
C
3 and 4
D
1 and 3
In the gate area for non-pressurized casting gating ratio a:b:c? (gating ratio = a: b: c where, a = cross-sectional area of sprue, b: cross-sectional area of runner, c = total cross-sectional area of ingates).
A
1:2:2
B
2:2:1
C
1:4:4
D
1:4:2