Fluid Mechanics (301-320)

Updated: Apr 22, 2020

301.In the set up shown in Fig, assuming the specific weight of water as 10,000

N/m³ the pressure difference between the points A and B will be


-10 N/m²

 

302 .Pumps in series operation allow the head to increase

Pumps in parallel operation increase the flow rate.

 

303. Which one of the following can be a set of velocity components of a two-dimensional flow? u = x + y and v = x - y

 

304 Specific Speed

A. Pelton 25

B. Propeller 900

C. Kaplan 800

D. Francis 75

 

305. The height of a hydraulic jump in a stilling pool was found to be 10 cm in a

model with l/l =36. The prototype jump height would be 3.6 m


 

306. To generate 10,000 hp under a head of 81 m while working at a speed of

500 rpm, the turbine of choice would be Francis


 

307 Runaway speed of a turbine is generally 180% of normal speed

Underground power stations are suited to areas susceptible to land slides

 

308. A pressure increase of 200 N/cm² increases the density of water by 0.1%.

The bulk modulus of elasticity of water is equal to 2 GN/m²

 

309. A Bourdon gauge measures the pressure at a point relative to the local atmospheric pressure and not relative to the standard atmospheric pressure

 

310. A slab of wood 4 m by 4 m by 1 m (height), specific gravity 0.50 floats in

water with 400 kg mass on it. The volume of the slab submerged , in cubic metres, is 8.4

 

311. Two small circular orifices of diameters d and d respectively are placed on one side of a tank at depths of 25 cm and 1 m below a constant surface of water. If the discharges through the orifices are the same, then the ratio of the diameter d and d will be 2:1


 

312. The streamlines of a flow net are concentric circles. If the velocity at a

radius of 0.6 m is 2.7 m/s, the velocity at a radius of 0.9 m will be 1.8 m/s

 

313.The following stream function will represent/satisfy



irrotational flow, Laplace equation and equation of continuity

 

314. Streamlines and equipontential lines are orthogonal wherever they meet


 

315. The time required to empty a concrete tank through a rectangular weir at the side from a head of 16 cm to 8 cm over the crest was found to be 16 minutes. The

time required to empty it further up to the crest will be Infinite


 

316. If two geometrically similar models having a scale ratio L are operated in a

given laboratory at the same Froude number, then all the corresponding

accelerations will be in the ratio of l


 

317. In the distored model of a river, the horizontal and vertical scale ratios are L

and L respectively. The discharge ratio will be

Lₕ Lᵥ³/²


 

318.











 

319. At the same mean velocity, the ratio of head loss per unit length for a sewer pipe flowing full to that for the same pipe flowing half full would be 1.0

 

320. The velocity of a pressure wave in water hammer is equal to the velocity of sound in water. Is this statement correct ?

No, because, the elasticity of the pipe reduces the velocity of the pressure

wave

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