Fluid Mechanics

261.If the discharge of a centrifugal pump is throttled, then its suction lift

1. Increases
2. Decreases
3. Remains unchanged
4. Data insufficient to predict

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262.If the head over the triangular notch is doubled, the discharge will increase by _________ times.

1. 2
2. 2.828
3. 5.657
4. 4

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263.If three pipes of different diameters, lengths & friction factors are connected in parallel, then (where, Q = flow rate, V= fluid velocity f = friction factor).

1. Q = Q₁ + Q₂ + Q₃
2. V₁ = v² = V₃
3. Q₁ = Q₂ = Q₃
4. f = f1 + f2 + f3

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264.If two capillary tubes of dia 0.5 mm and 1 mm are dipped in a pot containing mercury, then the rise of mercury is

1. Same in both the tubes
2. Greater in 1 mm dia tube
3. Greater in 0.5 mm dia tube
4. Zero in both the tubes

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265.In a dry packed bed, the pressure drop will be changed by increasing the flow rate as

1. V^1.8
2. V^-1.8
3. V
4. V^-1

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266.In a fluidised bed reactor

1. Temperature gradients are very high
2. Temperature is more or less uniform
3. Hot spots are formed
4. Segregation of the solids occurs

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267.In a free vortex, the

1. Velocity changes linearly with radial distance
2. Flow is necessarily rotational
3. Radial component of velocity is same everywhere
4. Stream lines are not circular

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268.In a fully turbulent flow (Re > 10⁵) in a pipe of diameter 'd', for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is

1. d
2. d²
3. d^2.5
4. d⁴

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269.In a stabilised soap bubble, pressure inside it compared to external pressure is

1. More
2. Less
3. Same
4. Unpredictable

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270.In a/an _________, the flow rate of fluids is obtained by measuring the difference between the impact and the static pressure.

1. Rotameter
2. Pitot tube
3. Venturimeter
4. Flow nozzle

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