Fluid Properties

Question 1

What’s a fluid?

Answer 1

A fluid is a substance in either the liquid or gas phase.

Question 2

What’s a modeled continuum?

Answer 2

A substance that can be divided into infinitesimally small volumes, with properties that are continuous functions over the entire volume.

Question 3

What’s the density?

Answer 3

It is the mass per unit volume of a fluid

Question 4

What’s the specific volume?

Answer 4

It’s the volume occupied by a unit of mass.

Question 5

What’s the specific weight?

Answer 5

It’s the weight of a substance per unit volume.

Question 6

What’s specific gravity?

Answer 6

Its the dimensionless ratio of a fluid’s density to the density of water or specific weight of the fluid to the specific weight of water.

Question 7

What’s absolute pressure?

Answer 7

The pressure measured with respect to a true zero pressure reference.

Question 8

What’s gage pressure?

Answer 8

The pressure measured with respect to atmospheric pressure.

Question 9

What is standard atmospheric pressure equal to?

Answer 9

Either 101.3 kPa or 29.9 inches of Mercury.

Question 10

How are atmospheric and gage pressure related?

Answer 10

The absolute pressure is equal to the addition of the atmospheric pressure and gage pressure.

Question 11

What are barometric pressures?

Answer 11

Barometric pressures are atmospheric pressures.

Question 12

What is a vacuum pressure measurement?

Answer 12

It’s a negative gage pressure.

Question 13

How are atmospheric and vacuum gage pressure related?

Answer 13

The absolute pressure is equal to the difference of the atmospheric pressure and vacuum gage pressure.

Question 14

What is stress?

Answer 14

It is the force per unit area.

Question 15

How many types of stress are exist and what are they?

Answer 15

Two. Normal stress and shear stress.

Question 16

What is normal stress?

Answer 16

In normal stress the area is normal to the force.

Question 17

What is tangential or shear stress?

Answer 17

In shear stress the area is parallel to the force.

Question 18

How are Normal stress and pressure related?

Answer 18

The normal stress is equal to the pressure of the fluid.

Question 19

What is the viscosity of a fluid?

Answer 19

Is a measure of that fluid’s resistance to flow when acted upon by an external force.

Question 20

What is Newton’s Law of Viscosity?

Answer 20

Its the equation used to find the shear stress for Newtonian fluids.

Question 21

What are Newtonian fluids?

Answer 21

Strains are proportional to the applied shear stress. The stress versus strain curve is a straight line.

Question 22

What is the Power Law?

Answer 22

Its the equation used to find the shear stress for non Newtonian fluids.

Question 23

What are non Newtonian fluids?

Answer 23

Fluids that have viscosity that change with shear rate.

Question 24

How many Non Newtonian fluids exist and what are they?

Answer 24

There are two non Newtonian fluids and they are pseudo plastic fluids and dilatant fluids.

Question 25

What are pseudo plastic fluids?

Answer 25

Fluids that exhibit a decrease in viscosity the faster they are agitated.

Question 26

What are dilitant fluids?

Answer 26

Fluids that exhibit an increase in viscosity the faster they are agitated.

Question 27

What is kinematic viscosity?

Answer 27

Is the absolute viscosity divided by the mass density.

Question 28

What is surface tension?

Answer 28

The tensile force between two points a unit distance apart.

Question 29

What is capillary action?

Answer 29

The action caused surface tension between the liquid and a vertical solid surface.

Question 30

How many capillary actions are there and what are they?

Answer 30

There are 2 capillary actions and they are capillary rise and depression.

Question 31

What are adhesive forces?

Answer 31

Are the attractive forces between the liquid and solid surfaces.

Question 32

What are cohesive forces?

Answer 32

The attractive forces between the water molecules themselves.

Question 33

What is a meniscus?

Answer 33

The curved surface of the liquid caused by the adhesive or cohesive forces.

Question 34

What is a capillary rise?

Answer 34

When the adhesive forces dominate and the meniscus is above the general liquid surface level.

Question 35

What is a capillary depression?

Answer 35

When the cohesive forces dominate and the meniscus is below the general liquid surface level.

Question 36

What is the angle of contact?

Answer 36

Is an indicator of whether adhesive or cohesive forces dominate.

Question 37

When does the angle of contact indicate adhesive and cohesive dominance?

Answer 37

For contact angles less than 90 degrees adhesive forces dominate for angles greater than 90 degrees cohesive angles dominate.

Question 38

What does the capillary equation determine?

Answer 38

The capillary equation determines the height of the rise or depression.

Question 39

What does a positive or negative capillary equation result determine?

Answer 39

A positive determines a rise and negative a depression for the meniscus.