Fluid Mechanics MCQs

121. Select the correct statement.

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The discharge through a venturimeter depends upon ?p only and is independent of orientation of the meter
A venturimeter with a given gage difference discharges at a greater rate, when the flow is vertically downward through it, than when the flow is vertically upward
For a given pressure difference, the discharge of gas is greater through a venturimeter, when compressibility is taken into account, than when it is neglected
The overall pressure loss is the same in a given pipe line, whether a venturimeter or a nozzle with the same throat dia is used
✅ The correct answer is option A.

127. A gas (density = 1.5 kg/m³ , viscosity = 2x 10⁻⁵ kg/m.s) flowing through a packed bed (particle size = 0.5 cm, porosity = 0.5) at a superficial velocity of 2 m/s causes a pressure drop of 8400 Pa/m. The pressure drop for another gas, with density of 1.5kg/m³and viscosity of 3 x 10⁻⁵kg/m.s flowing at 3 m/s will be

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8400 Pa/m
12600 Pa/m
18900 Pa/m
16800 Pa/m
✅ The correct answer is option B.

128. The location of centre of pressure, which defines the point of application of the total pressure force on the surface, can be calculated by applying the principle of moments according to which “sum of the moment of the resultant force about an axis is equal to the sum of the components about the same axis”. The centre of pressure of a rectangular surface (of width ‘w’) immersed vertically in a static mass of fluid is at a depth of(where, y = depth of the liquid)

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1/3y
2y/3
1/4y
3y/4
✅ The correct answer is option B.