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Questions and Answers
What is the physical parameter that can be defined using Poiseuille's law?
What is the physical parameter that can be defined using Poiseuille's law?
What is the purpose of dividing the equation for one liquid by the equation for the second liquid in Poiseuille's law for two fluids?
What is the purpose of dividing the equation for one liquid by the equation for the second liquid in Poiseuille's law for two fluids?
What is the assumption made when applying Poiseuille's law to two fluids?
What is the assumption made when applying Poiseuille's law to two fluids?
What is the purpose of using a liquid of known density and viscosity, such as water, in Poiseuille's law?
What is the purpose of using a liquid of known density and viscosity, such as water, in Poiseuille's law?
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What is the unit of measurement for the acceleration due to gravity (g) in Poiseuille's law?
What is the unit of measurement for the acceleration due to gravity (g) in Poiseuille's law?
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What is the term that groups all constant parameters in Poiseuille's law?
What is the term that groups all constant parameters in Poiseuille's law?
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What is the study of the flow and deformation properties of matter?
What is the study of the flow and deformation properties of matter?
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What is the resistance of a fluid to flow or movement?
What is the resistance of a fluid to flow or movement?
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Which of the following fluids is easier to stir or pour?
Which of the following fluids is easier to stir or pour?
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What is the main objective of studying rheology in pharmaceutical formulations?
What is the main objective of studying rheology in pharmaceutical formulations?
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What is the unit of shear stress?
What is the unit of shear stress?
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What is the main difference between Newtonian and non-Newtonian fluids?
What is the main difference between Newtonian and non-Newtonian fluids?
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What is the relationship between shear rate and shear stress in a Newtonian fluid?
What is the relationship between shear rate and shear stress in a Newtonian fluid?
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What is a common application of rheology?
What is a common application of rheology?
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What is the dimension of dynamic viscosity?
What is the dimension of dynamic viscosity?
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What is the difference between shear stress and pressure?
What is the difference between shear stress and pressure?
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What is the unit of kinematic viscosity?
What is the unit of kinematic viscosity?
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What is the characteristic of a fluid with a steeper curve in a viscosity graph?
What is the characteristic of a fluid with a steeper curve in a viscosity graph?
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What is the unit of viscosity in the given table?
What is the unit of viscosity in the given table?
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What type of fluids obey Newton's law?
What type of fluids obey Newton's law?
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What is the characteristic of a Non-Newtonian fluid?
What is the characteristic of a Non-Newtonian fluid?
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What is the name of the flow type characterized by a yield value (σy)?
What is the name of the flow type characterized by a yield value (σy)?
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What is the term for the apparent viscosity at a defined shear stress value and temperature?
What is the term for the apparent viscosity at a defined shear stress value and temperature?
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Which of the following is an example of a Pseudoplastic fluid?
Which of the following is an example of a Pseudoplastic fluid?
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What is the unit of measurement for dynamic viscosity?
What is the unit of measurement for dynamic viscosity?
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How can the dynamic viscosity of a Newtonian fluid be obtained from a plot of shear rate vs shear stress?
How can the dynamic viscosity of a Newtonian fluid be obtained from a plot of shear rate vs shear stress?
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What is the correct statement about the power law?
What is the correct statement about the power law?
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What is the unit of measurement for shear stress?
What is the unit of measurement for shear stress?
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What is the relationship between shear rate and shear stress in a plot for a Newtonian fluid?
What is the relationship between shear rate and shear stress in a plot for a Newtonian fluid?
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Study Notes
Rheology and Viscosity
- Rheology is the study of the flow and deformation properties of matter.
- Viscosity is the resistance of a fluid to flow or movement.
Poiseuille's Law
- For a liquid flowing through a capillary tube, Poiseuille's law states that the viscosity of the fluid is proportional to the pressure difference, radius of the capillary, and length of the capillary, and inversely proportional to the volume of the liquid.
- The law can be simplified to η = (k * P * L) / (8 * V * t), where η is the viscosity, k is a constant, P is the pressure difference, L is the length of the capillary, V is the volume of the liquid, and t is the time of flow.
- Poiseuille's law can be used to compare the viscosity of two fluids, where the ratio of the viscosities of the two fluids is equal to the ratio of their flow times.
Viscosity Measurement
- The viscosity of a fluid can be measured using a viscometer, which consists of a capillary tube and a pressure difference.
- The flow time of a fluid through the capillary tube is proportional to its viscosity.
Types of Fluids
- Newtonian fluids have a constant viscosity, which means their shear rate is directly proportional to the shear stress.
- Non-Newtonian fluids have a viscosity that changes with the shear stress, and their behavior can be described by different types of flow, including plastic, pseudoplastic, and dilatant flow.
Non-Newtonian Fluids
- Plastic or Bingham flow: the fluid does not flow until a minimum stress (yield value) is applied, and the relationship between shear stress and shear rate is not linear.
- Pseudoplastic flow: the fluid flows as soon as the shear stress is applied, and the viscosity changes with the shear stress, making it a "shear thinning" fluid.
- Dilatant flow: the fluid's viscosity increases with the shear stress, making it a "shear thickening" fluid.
Key Concepts
- Shear stress (σ) is the tangential force applied per unit of surface area, measured in N/m2.
- Shear rate (γ) is the rate at which the velocity of flow decreases, measured in s-1.
- Dynamic viscosity (η) is the coefficient of proportionality between the shear stress and shear rate, measured in Pa·s.
- Apparent viscosity is the viscosity of a non-Newtonian fluid at a defined shear stress value and temperature.
- The power law can be used to describe the behavior of non-Newtonian fluids, where the apparent viscosity is proportional to the shear stress raised to a power (n).
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Description
Test your knowledge on rheology, viscosity, and their importance in pharmaceutical formulations. Learn about Newtonian and non-Newtonian fluids and their behavior. Join the Vevox quiz to assess your understanding of these concepts.
