Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Hydraulics 1 > Fluid Properties > Flashcards

Fluid Properties Flashcards

1
Q

What is Hydraulics?

A

Branch of applied science and engineering which deals with mechanical properties and motion of fluids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is fluid dynamics?

A

Application of fundamental principles of general mechanics to fluids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are three mechanical properties of fluids?

A

Density, viscosity and surface tension.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the two types of motion for a fluid?

A

Closed conduits (pipes) which have no free surface and channels with a free surface.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the definition of a fluid?

A

A substance that continuously deforms or flows under an applied shear stress.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What can a fluid at rest not resist?

A

Shear stress.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a liquid?

A

A fluid which when placed in an open container, takes the shape of the container and has a free surface.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a gas?

A

A fluid which when placed in an open container expands to fill the container.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which is denser; liquid or gas?

A

Liquid, it contains more molecules per unit volume.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is density?

A

Mass of a given amount of a substance (m) to the volume it occupies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the density of water taken to be?

A

1000 kg/m^3.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does the exact density of water vary with?

A

Temperature, it’s 1000 kg/m^3 at 4 degrees Celsius.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the density of typical seawater with 35% salinity?

A

1025 kg/m^3.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is relative density/specific gravity?

A

The ratio of the density of a substance to that of pure water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the dimensions of relative density?

A

Dimensionless.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the unit weight of a substance?

A

The ratio of the weight of a given amount of a substance (W) to the volume it occupies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the SI units of unit weight?

A

N/m^3.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What causes pressure in a fluid?

A

Continual movement of molecules means that any part of a fluid experiences forces exerted by adjoining fluid or solid boundaries as a result of the action of innumerable molecular collisions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is pressure (p) equal to?

A

The normal force applied to a surface element of a fluid divided by its area.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the SI units of pressure?

A

Pascals (Pa) = N/m^2. Pressure can also be given in atmospheres, where 1 atm = 1.01325x10^5 Pa.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do instruments determine pressure?

A

Pressure cannot be measured directly. It is determined by the difference in pressure between two points.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the two types of reference pressure?

A

Absolute and gauge pressure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is absolute pressure?

A

Where pressure is given relative to pressure in a perfect vacuum.

24
Q

What is gauge (relative) pressure?

A

Where pressure is given relative to the local atmospheric pressure.

25
Q

Which form of pressure do meteorologists use?

A

Absolute as it ensures all values are positive.

26
Q

Which form of pressure do civil engineers normally use?

A

Gauge, as it is what is typically acting on structures.

27
Q

What is absolute pressure at sea level?

A

101.3kPa.

28
Q

What is compressibility of a fluid expressed by?

A

Bulk modulus of elasticity, E.

29
Q

What is bulk modulus of elasticity (E)?

A

The ratio of the increase in pressure to the resulting volumetric strain.

30
Q

What does an increase in pressure result in?

A

Higher density and reduced volume.

31
Q

What does a decrease in pressure result in?

A

Lower density and increased volume.

32
Q

Is bulk modulus of elasticity greater for liquids or gases?

A

Liquids.

33
Q

What is the bulk modulus of elasticity for water at 20 degrees Celsius?

A

2.2x10^9 Pa = 2.2 GPa

34
Q

What do we assume for the compressibiltiy of water?

A

That it’s incompressible and density is constant.

35
Q

What is the viscosity of a fluid?

A

A measure of its resistance to gradual deformation by shear or tensile stress.

36
Q

Will a more viscous fluid deform faster or slower than a less viscous fluid?

A

Slower.

37
Q

What is Newton’s law of viscosity?

A

Shear stress = dynamic viscosity (mew) x velocity gradient (du/dy).

38
Q

What are the SI units of dynamic viscosity?

A

Pa.s. Pascal seconds.

39
Q

What are Newtonian fluids?

A

Fluids that conform to Newton’s law of viscosity.

40
Q

What is viscosity dependent on for non-Newtonian fluids?

A

Rate of shear or shear history.

41
Q

What is a negative implication of non-Newtonian fluids?

A

If a house is built on clay and and earthquake puts stress on the ground, the clay can liquefy.

42
Q

What is a positive implication of non-Newtonian fluids?

A

Body armour has been developed that behaves like a liquid for easy movement, but becomes solid on impact.

43
Q

What is viscosity independent to?

A

Pressure changes.

44
Q

What is kinematic viscosity (new)?

A

Ratio of dynamic viscosity to density.

45
Q

What are the SI units of kinematic viscosity?

A

m^2/s.

46
Q

What causes surface tension?

A

Molecules on the surface of a fluid have no molecules above to have a cohesive force to thus cohere more strongly to other surface molecules, creating the effect of a membrane covering the surface.

47
Q

What is the effect of surface tension?

A

Things with a higher density than water, e.g. spider, can sit on the surface. They’re not floating as should sink.

48
Q

How does surface tension cause water to form into droplets?

A

Intermolecular forces mean that a small un-enclosed volume of liquid tends to be pulled into a spherical shape by cohesive forces on surface layer.

49
Q

What is surface tension usually measured in?

A

dynes/cm. 1 dyne/cm = 0.001 N/m

50
Q

What is adhesion?

A

The attractive force which occurs between the molecules of a liquid and a solid.

51
Q

What does the angle of contact of a liquid-gas interface with a solid surface depend on?

A

Relative magnitudes of adhesion of liquid molecules to solid molecules and the cohesion of the liquid molecules to each other.

52
Q

When is a solid surface said to be completely wetted?

A

When adhesion exceed cohesion, e.g. water and a clean glass surface.

53
Q

When is wetting negligible?

A

When cohesion greatly exceeds adhesion. E.g. mercury and glass.

54
Q

If the solid surface is wetted does the free liquid surface curve up or down?

A

Up, it curves down with negligible wetting.

55
Q

What causes capillary rise?

A

Surface tension and adhesion.

56
Q

What is capillary rise?

A

If a tube is sufficiently narrow and liquid adhesion is sufficiently strong, a meniscus will form and surface tension can support the weight of liquid in the tube and draw the liquid up the tube.

57
Q

When can capillary rise be negative?

A

If theta is greater than 90 degrees e.g. mercury in glass.

Hydraulics 1 (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions