fix typos
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@@ -17,22 +17,20 @@ uuid: 43e8eefa-567f-438b-b93d-63ae08e61d8f
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## What is a Fluid?
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- A fluid may be liquid, vapor, or gas
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- A fluid may be liquid, vapour, or gas
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- No permanent shape
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- Consists of atoms in random motion and continual collision
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- Easy to deform
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- Liquids have fixed volume, gasses fill up container
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- **A fluid is a substance for wich a shear stress tends to produce unlimited, continuous
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- **A fluid is a substance for which a shear stress tends to produce unlimited, continuous
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deformation**
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## Shear Forces
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- For a solid, application of shear stress causes a deformation which, if not too great (elastic),
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is not permanent and solid regains original positon
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- For a fluid, continuious deformation takes place as the molecules slide over each other until the
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is not permanent and solid regains original position
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- For a fluid, continuous deformation takes place as the molecules slide over each other until the
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force is removed
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- **A fluid is a substance for wich a shear stress tends to produce unlimited, continuous
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deformation**
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## Density
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@@ -51,7 +49,7 @@ uuid: 43e8eefa-567f-438b-b93d-63ae08e61d8f
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- Matter is not continuous on molecular scale
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- For fluids in constant motion, we take a time average
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- For most practical purposes, matter is considered to be homogenous and time averaged
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- For most practical purposes, matter is considered to be homogeneous and time averaged
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## Pressure
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@@ -77,7 +75,7 @@ uuid: 43e8eefa-567f-438b-b93d-63ae08e61d8f
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- A fluid at rest has constant pressure horizontally
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- That's why liquid surfaces are flat
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- But fluids at rest do have a vertical gradient, where lower parts have higher presure
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- But fluids at rest do have a vertical gradient, where lower parts have higher pressure
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### How Does Pressure Vary with Depth?
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@@ -116,11 +114,11 @@ The -ve sign indicates that as $z$, height, increases, $p$, pressure, decreases.
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### Absolute and Gauge Pressure
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- Absolute Pressure is measured relative to zero (a vacuum)
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- Guage pressure = absolute pressure - atmospheric pressure
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- Gauge pressure = absolute pressure - atmospheric pressure
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- Often used in industry
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- If abs. pressure = 3 bar and atmospheric pressure is 1 bar, then gauge pressure = 2 bar
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- If absolute pressure = 3 bar and atmospheric pressure is 1 bar, then gauge pressure = 2 bar
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- Atmospheric pressure changes with altitude
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## Compressibility
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@@ -132,7 +130,7 @@ The -ve sign indicates that as $z$, height, increases, $p$, pressure, decreases.
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## Surface Tension
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- In a liquid, molecules are held together by molecular attraction
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- At a boundry between two fluids this creates "surface tension"
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- At a boundary between two fluids this creates "surface tension"
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- Surface tension usually has the symbol $$\gamma$$
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## Ideal Gas
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@@ -155,7 +153,7 @@ The -ve sign indicates that as $z$, height, increases, $p$, pressure, decreases.
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- Pressure always in Pa
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- Temperature always in K
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## Units and Dimentional Analysis
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## Units and Dimensional Analysis
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- It is usually better to use SI units
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- If in doubt, DA can be useful to check that your answer makes sense
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@@ -289,7 +287,7 @@ p_1 - p_2 &= \rho_wg(z_C-z_B-z_C+z_A) + \rho_mg\Delta z \\
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the upper surface (figure 1.4). The tank and riser are filled with
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water such that the water level in the riser pipe is 3.5 m above the
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Calulate:
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Calculate:
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i. The gauge pressure at the base of the tank.
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@@ -299,7 +297,7 @@ p_1 - p_2 &= \rho_wg(z_C-z_B-z_C+z_A) + \rho_mg\Delta z \\
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> $$\rho gh = 1000\times9.81\times3.5 = 34 \text{ kPa}$$
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iii. The force exercted on the base of the tank due to gauge water pressure.
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iii. The force exerted on the base of the tank due to gauge water pressure.
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> $$F = p\times A = 49\times10^3\times6\times3 = 8.8\times10^5 \text{ N}$$
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@@ -345,7 +343,7 @@ p_1 - p_2 &= \rho_wg(z_C-z_B-z_C+z_A) + \rho_mg\Delta z \\
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## Submerged Surfaces
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### Prepatory Maths
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### Preparatory Maths
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#### Integration as Summation
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@@ -370,7 +368,7 @@ Take the following lamina:
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1. Split the lamina into elements parallel to the chosen axis
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2. Each element has area $\delta A = w\delta y$
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3. The moment of area ($\delta M$) of the element is $\delta Ay$
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4. The sum of moments of all the elements is equal to the moment $M$ obtained by assuing all the
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4. The sum of moments of all the elements is equal to the moment $M$ obtained by assuming all the
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area is located at the centroid or:
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$$Ay_c = \int_{area} \! y\,\mathrm{d}A$$
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@@ -426,7 +424,7 @@ Determine the location of the centroid of a rectangular lamina.
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</details>
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### Horizontal Submereged Surfaces
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### Horizontal Submerged Surfaces
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@@ -492,12 +490,12 @@ Where $\rho$ is the density of the fluid, and $V$ is the volume of displaced flu
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### Immersed Bodies
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As pressure increases with depth, the fluid exerts a resultant upward force on a body.
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There is no horizontal component of the buoyancy force because the vertiscal projection of the body
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There is no horizontal component of the buoyancy force because the vertical projection of the body
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is the same in both directions.
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### Rise, Sink, or Float?
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- $F_B = W$ \rightarrow equilirbrium (floating)
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- $F_B = W$ \rightarrow equilibrium (floating)
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- $F_B > W$ \rightarrow body rises
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- $F_B < W$ \rightarrow body sinks
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