Fluid dynamics questions | form five Physics

1. Explain the terms lines of flow and streamlines when applied to fluid flow and deduce the relationship between them in laminar flow.
2. State Bernoulli`s equation , define the physical quantities which appear in it and the conditions required for its validity.
3. The depth of water in a tank of large cross-sectional area is maintained at 20 cm and water emerges in a continuous stream out of a hole 5 mm in diameter in the base.

Calculate:

1. The speed of efflux of water from the hole,
2. The rate of mass flow of water from the hole Given that density of water is 1.00 x 10³ kgm^-3

Answer / Solution

UNSOLVED

1. Distinguish between static pressure, dynamic pressure and total pressure when applied to streamline (laminar) fluid flow and write down expressions for these three pressures at a point in the fluid in terms of the flow velocity , the fluid density , pressure p and the height h, of the point with respect to a datum.
2. Describe , with the aid of a labelled diagram, the Pitot-static tube and explain how it may be used to determine the flow velocity of an incompressible, non-viscous fluid.
3. The static pressure in a horizontal pipeline is 4.3 x 10⁴ Pa, the total pressure is 4.7 x 10⁴ Pa, and the area of cross-section is 20 cm² . The fluid may be considered to be incompressible and non-viscous and has a density of 10³kg m^-3.

Calculate

1. The flow velocity in the pipeline
2. The volume flow rate in the pipeline.

Answer / Solution

UNSOLVED

Air flows over the upper surfaces of the wings of an aeroplane at a speed of 120.0ms^-1, and past the lower surfaces of the wings at 120.0ms^-1. Calculate the lift force on the aeroplane if it has a total wing area of 20.0m². (density of air=1.29kgm^-3)

Answer / Solution

UNSOLVED

A large tank contains water to a depth of 1.0m. Water emerges from a small hole in the side of the tank 20cm below the level of the surface. Calculate:

1. The speed at which the water emerges from the hole,
2. The distance from the base of the tank at which the water strikes the floor on which the tank is standing.

If a second hole were to be drilled in the wall of the tank vertically below the first hole, at what height above the base of the tank would this second hole have to be if the water issuing from it were to hit the floor at the same point as that from the first hole?

Answer / Solution

UNSOLVED

The principle of fluid pressure which is used in hydraulic brakes, is the

1. Pressure is the same at all levels in a fluid
2. Increase of pressure is transmitted equally to all parts of a fluid
3. The pressure at a point in a fluid is due to the weight of the fluid above it.
4. Increase of pressure can only be transmitted trhough fluids.
5. The pressure at a given depth is proportional to the depth in the fluid.

Answer / Solution

UNSOLVED