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Questions and Answers
What occurs when the pressure above a liquid surface is reduced to equal or below its vapor pressure?
What occurs when the pressure above a liquid surface is reduced to equal or below its vapor pressure?
Which type of pressure is measured above absolute zero or vacuum?
Which type of pressure is measured above absolute zero or vacuum?
What is the primary cause of cavitation in a flowing liquid?
What is the primary cause of cavitation in a flowing liquid?
What distinguishes gauge pressure from absolute pressure?
What distinguishes gauge pressure from absolute pressure?
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What device is considered a simple manometer for measuring fluid pressure?
What device is considered a simple manometer for measuring fluid pressure?
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In the context of cavitation, what happens to the vapor bubbles when they enter a region of higher pressure?
In the context of cavitation, what happens to the vapor bubbles when they enter a region of higher pressure?
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What is a defining feature of vacuum pressure?
What is a defining feature of vacuum pressure?
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Which mechanical gauge type uses a spring or dead weight in measurement?
Which mechanical gauge type uses a spring or dead weight in measurement?
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Why is it significant that the vapor pressure changes with temperature?
Why is it significant that the vapor pressure changes with temperature?
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What is the primary characteristic of an ideal fluid?
What is the primary characteristic of an ideal fluid?
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Which type of fluid is characterized by shear stress being directly proportional to the rate of shear strain?
Which type of fluid is characterized by shear stress being directly proportional to the rate of shear strain?
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What defines kinematic viscosity?
What defines kinematic viscosity?
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In the equation $ au = \mu (du/dy)$, what does $ au$ represent?
In the equation $ au = \mu (du/dy)$, what does $ au$ represent?
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Which equation describes the pressure inside a droplet based on surface tension?
Which equation describes the pressure inside a droplet based on surface tension?
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How does capillary rise occur in a thin tube?
How does capillary rise occur in a thin tube?
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What condition does the equilibrium state describe when discussing liquid height in capillarity?
What condition does the equilibrium state describe when discussing liquid height in capillarity?
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How is the capillary rise in a tube expressed mathematically?
How is the capillary rise in a tube expressed mathematically?
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What phenomenon is described by the change from the liquid state to the gaseous state?
What phenomenon is described by the change from the liquid state to the gaseous state?
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What is the effect of surface tension on a hollow bubble?
What is the effect of surface tension on a hollow bubble?
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Which type of fluid would most likely not demonstrate Newton's law of viscosity?
Which type of fluid would most likely not demonstrate Newton's law of viscosity?
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What occurs to the pressure intensity when a liquid jet is examined?
What occurs to the pressure intensity when a liquid jet is examined?
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What is the relationship between shear stress and shear strain in Newtonian fluids?
What is the relationship between shear stress and shear strain in Newtonian fluids?
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What principle defines the relationship of shearing motion in fluids?
What principle defines the relationship of shearing motion in fluids?
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What is the unit of measurement for specific weight or specific density?
What is the unit of measurement for specific weight or specific density?
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Which statement correctly defines specific gravity?
Which statement correctly defines specific gravity?
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How is mass density calculated?
How is mass density calculated?
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Which of the following units is equivalent to 1 Pascal?
Which of the following units is equivalent to 1 Pascal?
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What is the relationship between a Joule and a Watt?
What is the relationship between a Joule and a Watt?
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If a fluid has a density of 800 kg/m³, what would its specific gravity be when compared to water?
If a fluid has a density of 800 kg/m³, what would its specific gravity be when compared to water?
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According to Newton's second law of motion, what is the force in Newtons for a mass of 2 kg that is accelerated at 3 m/s²?
According to Newton's second law of motion, what is the force in Newtons for a mass of 2 kg that is accelerated at 3 m/s²?
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What does the term 'specific volume' refer to?
What does the term 'specific volume' refer to?
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Study Notes
Fluid Mechanics Units and Properties
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Dimensions and Units: Dimensions describe measurable characteristics (mass, length, temperature). Units are standardized measurements for dimensions. Fundamental dimensions are mass (kg), length (m), time (s), and temperature (Kelvin or °C).
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Density (ρ): Mass per unit volume (kg/m³). Water's density is 1000 kg/m³. ρ = mass of fluid / volume of fluid
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Specific Weight (w): Weight per unit volume (N/m³). w = weight of fluid / volume of fluid
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Specific Volume: Volume per unit mass (m³/kg). Specific volume = volume of fluid / mass of fluid.
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Specific Gravity (S): Ratio of a fluid's density to a reference fluid's density (dimensionless). For liquids, water is the reference. For gases, air is the reference. Specific Gravity = weight density of liquid/ weight density of water
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Viscosity (μ): Resistance to fluid layer movement. Shear stress (τ) is proportional to the velocity gradient (du/dy). τ = μ (du/dy). Newtonian fluids obey this relationship; Non-Newtonian fluids do not.
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Kinematic Viscosity (ν): Ratio of dynamic viscosity to density. ν = μ/ρ
Types of Fluids
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Ideal Fluid: Imaginary fluid with zero viscosity and incompressibility.
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Real Fluids: Possess viscosity, found in practice.
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Newtonian Fluids: Stress is directly proportional to the rate of shear strain.
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Non-Newtonian Fluids: Stress isn't proportional to the rate of shear strain.
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Ideal Plastic Fluids: Shear stress exceeds a yield value, and then is proportional to the shear strain rate.
Surface Tension
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Surface Tension (σ): Tensile force on a liquid surface, acting between the liquid and a surrounding gas, or behaves as a stretched membrane. Measured in N/m.
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Surface Tension on a Liquid Droplet: Internal pressure (p) is related to surface tension and droplet diameter (d): p = 4σ/d.
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Surface Tension on a Hallow Bubble: Internal pressure of a bubble is related to surface tension and diameter: p = 8σ/d.
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Surface Tension on a Liquid Jet: Internal pressure (p) of a liquid jet is related to surface tension and diameter: p = 2σ/d
Capillarity
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Capillarity: Rise or fall of a liquid in a small tube due to surface tension.
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Capillary Rise (h): Height of liquid rise in a tube. h = 4σ cosθ / (ρgd) where σ is surface tension, θ is contact angle, ρ is density, g is acceleration due to gravity, and d is tube diameter
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Capillary Fall: A fall of liquid level in a tube, happens with materials where the contact angle between liquid and tube is greater than 90°
Vapor Pressure and Cavitation
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Vapor Pressure: Pressure exerted by a liquid's vapor when vaporization occurs
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Cavitation: Formation and collapse of vapor bubbles in a liquid due to low pressure. Leads to erosion.
Pressure Measurement
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Absolute Pressure: Pressure relative to a complete vacuum.
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Gauge Pressure: Pressure relative to atmospheric pressure.
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Vacuum Pressure: Pressure below atmospheric pressure.
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Manometers: Devices measuring pressure by balancing fluid columns.
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Mechanical Gauges: Measuring pressure by springs or dead weights e.g., diaphragm gauges, Bourdon tube gauges.
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Description
Explore the fundamental concepts of fluid mechanics including dimensions, units, and properties such as density, specific weight, and viscosity. This quiz covers key formulas and definitions necessary for understanding fluid behavior in different contexts. Test your knowledge and solidify your grasp on these essential principles.
