Physics of Viscosity Quiz
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Questions and Answers

Which of the following statements best defines viscosity?

  • The density of a fluid.
  • The ability of a fluid to conduct electricity.
  • A measure of the resistance of a fluid to flow. (correct)
  • The temperature at which a fluid boils.

    • All fluids possess some viscosity.

    True

    What are the two main types of viscosity?

    Dynamic viscosity and kinematic viscosity

    Glycerine and castor oil are examples of fluids with _______ viscosity.

    <p>high</p> Signup and view all the answers

    Which of the following is a characteristic of non-Newtonian fluids?

    <p>Their viscosity changes with the applied shear rate.</p> Signup and view all the answers

    Match the following fluids with their viscosity characteristics:

    <p>Glycerine = High viscosity Water = Low viscosity Tar = Very high viscosity Kerosene = Low viscosity</p> Signup and view all the answers

    What is Newton's Law of Viscosity primarily concerned with?

    <p>The relationship between shear stress and shear rate in fluids.</p> Signup and view all the answers

    The two systems for measuring viscosity grades commonly used are SAE and _______ viscosity grades.

    <p>ISO</p> Signup and view all the answers

    What is the viscosity of a fluid measured in stokes when it is equal to 0.001 m²/s?

    <p>1 stoke</p> Signup and view all the answers

    Viscosity of liquids increases with heating.

    <p>False</p> Signup and view all the answers

    What type of fluid has zero viscosity?

    <p>Ideal fluid</p> Signup and view all the answers

    For gases, viscosity __________ with an increase in temperature.

    <p>increases</p> Signup and view all the answers

    Match each type of fluid with its characteristic:

    <p>Ideal fluid = Zero viscosity, incompressible Real fluid = All types of fluids Newtonian fluid = Fluid whose viscosity remains constant under varying shear rates Non-Newtonian fluid = Fluid whose viscosity changes under different shear rates</p> Signup and view all the answers

    Alcohol is an example of a Newtonian fluid.

    <p>False</p> Signup and view all the answers

    What measurement unit is equivalent to 1 centistoke (cSt)?

    <p>0.000001 m²/s</p> Signup and view all the answers

    What is the SI unit of dynamic viscosity?

    <p>Pa.s</p> Signup and view all the answers

    Kinematic viscosity is defined as the ratio of dynamic viscosity to the density of the fluid.

    <p>True</p> Signup and view all the answers

    What does the variable 'μ' represent in the equation τ = μ (du/dy)?

    <p>coefficient of viscosity or dynamic viscosity</p> Signup and view all the answers

    The unit of kinematic viscosity in CGS is called _______.

    <p>stoke</p> Signup and view all the answers

    Which of the following is NOT an application of viscosity?

    <p>Heat transfer in metals</p> Signup and view all the answers

    Match the following types of viscosity with their definitions:

    <p>Dynamic viscosity = Ratio of shear stress to shear strain rate Kinematic viscosity = Ratio of dynamic viscosity to density</p> Signup and view all the answers

    The coefficient of viscosity is also known as the dynamic viscosity.

    <p>True</p> Signup and view all the answers

    The formula for dynamic viscosity is given by τ = μ (du/dy), where τ represents _______.

    <p>shear stress</p> Signup and view all the answers

    Which of the following fluids are classified as Newtonian fluids?

    <p>Water</p> Signup and view all the answers

    Non-Newtonian fluids obey Newton's law of viscosity.

    <p>False</p> Signup and view all the answers

    What is the purpose of the viscosity index (VI)?

    <p>To show how the viscosity of a fluid changes with temperature.</p> Signup and view all the answers

    Fluids that do not follow Newton's viscosity law are called ___.

    <p>Non-Newtonian fluids</p> Signup and view all the answers

    Match the following viscometers with their type:

    <p>Rotating drum viscometer = Rotational measurement Capillary tube viscometer = Capillary action measurement Falling-ball viscometer = Falling ball measurement Saybolt Universal viscometer = Time-based measurement</p> Signup and view all the answers

    What does the first number in SAE-15W refer to?

    <p>Viscosity at low temperature</p> Signup and view all the answers

    Saybolt Universal Seconds (SUS) measure the viscosity of fluids.

    <p>True</p> Signup and view all the answers

    Identify one kind of fluid that is classified as a Non-Newtonian fluid.

    <p>Honey</p> Signup and view all the answers

    How many ISO Viscosity grades are there for oils used in industries?

    <p>20</p> Signup and view all the answers

    ISO VG 22 refers to a viscosity grade of 22 cSt ± 10% at 40°C.

    <p>True</p> Signup and view all the answers

    What does the 'W' in SAE viscosity grades signify?

    <p>Winter viscosity</p> Signup and view all the answers

    The viscosity of a liquid is its resistance to _____ .

    <p>flow</p> Signup and view all the answers

    Match the following characteristics of hydraulic fluids with their definitions:

    <p>Non-corrosiveness = Does not cause damage to materials Chemical stability = Maintains properties over time Adequate viscosity = Sufficient thickness for lubrication Ecologically acceptable = Safe for the environment</p> Signup and view all the answers

    What is the formula for calculating the power of the shaft?

    <p>P = (2πNT) / 60</p> Signup and view all the answers

    Shear stress is calculated by dividing shear force by area.

    <p>True</p> Signup and view all the answers

    What is the significance of the first number in a SAE viscosity grade such as 15W/40?

    <p>It indicates the viscosity at cold temperatures.</p> Signup and view all the answers

    Study Notes

    Applied Fluid Mechanics (Unit 2): Viscosity of Fluids

    • Viscosity is a measure of a fluid's resistance to flow, or its internal resistance to flow.
    • It is a fluid property that resists the movement of one fluid layer over another.
    • All fluids have some resistance to flow, therefore all exhibit viscosity.
    • Viscosity is a crucial property in numerous applications, including:
      • Transparent and storage facilities for fluids (e.g., pipes, tanks)
      • Bitumen use in road construction
      • Design and analysis of sewer lines or other pipe flows
      • Oil and gas drilling
      • Maintaining machine and automobile performance by determining lubricant thickness.

    Viscosity of Fluids: Types

    • Dynamic viscosity (μ): Represents the internal resistance to flow of a fluid.
    • Kinematic viscosity (ν): Defined as the ratio of dynamic viscosity to the fluid's density.

    Viscosity: Measurement

    • Viscometers or Rheometers measure fluid viscosity.
    • Common types of viscometers include:
      • Rotating drum viscometer
      • Capillary tube viscometer
      • Falling-ball viscometer
      • Saybolt Universal viscometer

    Viscosity: Variations

    • With temperature:
      • Liquids: Viscosity decreases as temperature increases.
      • Gases: Viscosity increases as temperature increases.
    • Generally independent of pressure (for incompressible fluids).

    Viscosity: Newtonian vs. Non-Newtonian Fluids

    • Newtonian fluids: Fluids that obey Newton's Law of Viscosity (shear stress is directly proportional to the rate of shear strain). Examples include water, air and kerosene.
    • Non-Newtonian fluids: Fluids that do not obey Newton's Law of Viscosity. Examples include honey, paints, and some drilling fluids.

    Viscosity Index (VI)

    • Viscosity index (VI) shows how viscosity changes with temperature.
    • Important for lubricating oils and hydraulic fluids used in equipment operating at extreme temperatures.

    SAE Viscosity Grades

    • SAE viscosity grades are used to categorize engine oils and automobile lubricants.
    • The first number of an SAE viscosity grade (e.g., SAE 15W40) refers to viscosity at low temperatures, while the second number (40) refers to viscosity at 100°C.

    ISO Viscosity Grades

    • ISO viscosity grades are used for industrial oils.
    • The designation is ISO VG (e.g., ISO VG 22), followed by a number representing the nominal kinematic viscosity in cSt (mm²/s) at 40°C.

    Characteristics of Hydraulic Fluids

    • Adequate viscosity: Necessary for proper functioning.
    • Lubricating capability: The fluid must lubricate components.
    • Cleanliness: Crucial for preventing contamination.
    • Chemical stability: The fluid must maintain its properties over time.
    • Non-corrosiveness: The fluid shouldn't corrode equipment.
    • Ability to resist bacterial growth: Necessary for preventing biofouling.
    • Ecologically acceptable: Environmentally friendly materials.
    • Low compressibility: Essential for maintaining pressure in hydraulic systems

    Newton's Law of Viscosity

    • A force is required to move a fluid layer atop another fluid layer.
    • Shear stress is proportionally related to the velocity gradient or shear strain.
    • Velocity (u) = (πDN)/60
    • Shear stress = Shear Force/Area
    • Area = πdL
    • Torque (T) = radius of the shaft * Shear force
    • Power (P) = (2πNT)/60

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    Applied Fluid Mechanics (Unit 2) Viscosity of Fluids PDF

    Description

    Test your understanding of viscosity with this quiz focused on fluid dynamics. Explore key concepts such as Newton's Law of Viscosity, types of fluids, and various measurement units. Perfect for students studying physics or engineering.

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