Fluid Mechanics (Set 1) | Multiple Choice Questions

1. When a body is placed over a liquid, it will sink down if

Gravitational force is equal to the up-thrust of the liquid

Gravitational force is less than the up-thrust of the liquid

Gravitational force is more than the up-thrust of the liquid

None of the above

2. The property by virtue of which a liquid opposes relative motion between its different layers is called

Surface tension

Coefficient of viscosity

Viscosity

Osmosis

3. A weir is said to be narrow-crested weir, if the width of the crest of the weir is __________ half the height of water above the weir crest.

Equal to

Less than

More than

None of these

4. Euler's dimensionless number relates the following

Inertial force and gravity

Viscous force and inertial force

Viscous force and buoyancy force

Pressure force and inertial force

5. When a body floating in a liquid, is displaced slightly, it oscillates about

C.G. of body

Center of pressure

Center of buoyancy

Metacentre

6. The pressure of the liquid flowing through the divergent portion of a Venturimeter

Remains constant

Increases

Decreases

Depends upon mass of liquid

7. When the Mach number is between __________ the flow is called super-sonic flow.

1 and 2.5

2.5 and 4

4 and 6

1 and 6

8. In an immersed body, centre of pressure is

At the centre of gravity

Above the centre of gravity

Below be centre of gravity

Could be above or below e.g. depending on density of body and liquid

9. A vertically immersed surface is shown in the below figure. The distance of its centre of pressure from the water surface is

A

B

C

D

10. The torque required to overcome viscous resistance of a collar bearing is (where R₁ andR₂ = External and internal radius of collar)

(μπ²N/60t) × (R₁ - R₂)

(μπ²N/60t) × (R₁² - R₂²)

(μπ²N/60t) × (R₁³ - R₂³)

(μπ²N/60t) × (R₁⁴ - R₂⁴)