Chapter 4.3

Question 1

What is viscosity? How does it relate to viscous drag?

Answer 1

• viscosity is resistance to a fluids flow
• > increases viscosity increases viscous drag
• note viscous drag is a nonconservative force
• all fluids are viscous to one degree or another

Question 2

What is laminar flow? Describe its characteristics

Answer 2

• it is smooth and orderly flow of liquid
• > they often flow parallel to each other

-layers will not necessarily have the same linear speed

Question 3

What is turbulent flow? Describe its characteristics. Also explain the relationship between turbulent flow and critical speed. Make sure to mention the term boundary layer.

Answer 3

-it is rough and disorderly

• in unobstructed flow, if critical speed is exceeded
• > turbulent flow can arise
• > laminar flow occurs only in the thin layer of fluid adjacent to the wall (boundary layer)
• note beyond the boundary layer= turbulent flow
• critical speed depends on the physical properties of the fluid, such as its viscosity and diameter of the tube

Question 4

What is a streamline?

Answer 4

• indicate the pathways followed by tiny fluid elements

- >sometimes fluid particles

Question 5

What is the velocity vector of a fluid equal to in relationship to the streamline?

Answer 5

• it will always be tangential to the streamline at any point
• > streamlines never cross each other

Question 6

How does flow rate change in a closed system? Is it dependent on the cross-sectional area

Answer 6

• flow rate(volume per unit of time) remains constant for a closed system
• > it is independent of the cross-sectional area

Question 7

How does linear speed change in a closed system? Is it dependent on the cross sectional area?

Answer 7

• linear speed(displacement of fluid particles per unit of time) does change
• > it does depend on the cross sectional area

Question 8

What does Bernoulli’s equation describe

Answer 8

• it is a statement of energy conservation
• > sum of the dynamic pressure and static pressure will be constant within a closed container for an incompressible fluid not experiencing viscous drag

-so if there is more dynamic pressure, then static pressure must decrease

Question 9

What two concepts does the Venturi effect combine

Answer 9

-it combines the Bernoulli equation and the continuity equation