Fluid Mechanics

71. Free surface of a liquid tends to contract to the smallest possible area due to force of

1. surface tension
2. viscosity
3. friction
4. cohesion
5. adhesion.

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72. Froude number is significant in

1. supersonics, as with projectile and jet propulsion
2. full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.
3. simultaneous motion through two fluids where there is a surface of dis-continuity, gravity forces, and wave making effect, as with ship's hulls
4. all of the above
5. none of the above

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73. General energy equation holds for

1. steady flow
2. turbulent flow
3. laminar flow
4. non-uniform flow
5. all of the above.

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74. Gradually varied flow is

1. steady uniform
2. non-steady non-uniform
3. non-steady uniform
4. steady non-uniform
5. true one-dimensional.

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75. Hot wire anemometer is used to measure

1. pressure in gases
2. liquid discharge
3. pressure in liquids
4. gas velocities
5. temperature.

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76. If 850 kg liquid occupies volume of one cubic meter, men 0.85 represents its

1. specific weight
2. specific mass
3. specific gravity
4. specific density
5. none of the above.

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77. If cohesion between molecules of a fluid is greater than adhesion between fluid and glass, then the free level of fluid in a dipped glass tube will be

1. higher than the surface of liquid
2. the same as the surface of liquid
3. lower than the surface of liquid
4. unpredictable
5. none of the above.

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78. If mercury in a barometer is replaced by water, the height of 3.75 cm of mercury will be following cm of water

1. 51 cm
2. 50 cm
3. 52 cm
4. 52.2 cm
5. 51.7 cm.

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79. If no resistance is encountered by displacement, such a substance is known as

1. fluid
2. water
3. gas
4. perfect solid
5. ideal fluid.

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80. If the atmospheric pressure on the surface of an oil tank (sp. gr. 0.8) is 0.2 kg/cm", the pressure at a depth of 50 m below the oil surface will be

1. 2 meters of water column
2. 3 meters of water column
3. 5 meters of water column
4. 6 meters of water Column
5. 7 meters of water column.

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