Fluid Mechanics

61. For a floating body to be in equilibrium

1. meta centre should be above e.g.
2. centre of buoyancy and e.g. must lie on same vertical plane
3. a righting couple should be formed
4. all of the above
5. none of the above.

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62. For a floating body to be in stable equilibrium, its metacentre should be

1. below the center of gravity
2. below the center of buoyancy
3. above the center of buoyancy
4. between e.g. and center of pressure
5. above the center of gravity.

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63. For hypersonic flow, the Mach number is

1. unity
2. greater than unity
3. greater than 2
4. greater than 4
5. greater than 10.

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64. For manometer, a better liquid combination is one having

1. higher surface tension
2. lower surface tension
3. surface tension is no criterion
4. high density and viscosity
5. low density and viscosity.

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65. For measuring flow by a venturimeter, if should be installed in

1. vertical line
2. horizontal line
3. inclined line with flow downward
4. inclined line with upward flow\
5. in any direction and in any location.

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66. For pipes, laminar flow occurs when Roynolds number is

1. less than 2000
2. between 2000 and 4000
3. more than 4000
4. less than 4000
5. none of the above.

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67. For pipes, turbulent flow occurs when Reynolds number is

1. less than 2000
2. between 2000 and 4000
3. more than 4000
4. less than 4000
5. none of the above.

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68. For similarity, in addition to models being geometrically similar to prototype, the following in both cases should also be equal

1. ratio of inertial force to force due to viscosity
2. ratio of inertial force to force due to gravitation
3. ratio of inertial force to force due to surface tension
4. all the four ratios of inertial force to force due to viscosity, gravitation, sur-face tension, and elasticity
5. all above.

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69. For very great pressures, viscosity of moss gases and liquids

1. remains same
2. increases
3. decreases
4. shows erratic behavior
5. none of the above.

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70. Free surface of a liquid behaves like a sheet and tends to contract to smallest possible area due to the

1. force of adhesion
2. force of cohesion
3. force of friction
4. force of diffusion
5. none of die above.

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