fix typos

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2022-03-08 11:15:34 +00:00
parent 35a4e42433
commit fe8a7209b3
3 changed files with 42 additions and 43 deletions

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@@ -17,22 +17,20 @@ uuid: 43e8eefa-567f-438b-b93d-63ae08e61d8f
## What is a Fluid?
- A fluid may be liquid, vapor, or gas
- A fluid may be liquid, vapour, or gas
- No permanent shape
- Consists of atoms in random motion and continual collision
- Easy to deform
- Liquids have fixed volume, gasses fill up container
- **A fluid is a substance for wich a shear stress tends to produce unlimited, continuous
- **A fluid is a substance for which a shear stress tends to produce unlimited, continuous
deformation**
## Shear Forces
- For a solid, application of shear stress causes a deformation which, if not too great (elastic),
is not permanent and solid regains original positon
- For a fluid, continuious deformation takes place as the molecules slide over each other until the
is not permanent and solid regains original position
- For a fluid, continuous deformation takes place as the molecules slide over each other until the
force is removed
- **A fluid is a substance for wich a shear stress tends to produce unlimited, continuous
deformation**
## Density
@@ -51,7 +49,7 @@ uuid: 43e8eefa-567f-438b-b93d-63ae08e61d8f
- Matter is not continuous on molecular scale
- For fluids in constant motion, we take a time average
- For most practical purposes, matter is considered to be homogenous and time averaged
- For most practical purposes, matter is considered to be homogeneous and time averaged
## Pressure
@@ -77,7 +75,7 @@ uuid: 43e8eefa-567f-438b-b93d-63ae08e61d8f
- A fluid at rest has constant pressure horizontally
- That's why liquid surfaces are flat
- But fluids at rest do have a vertical gradient, where lower parts have higher presure
- But fluids at rest do have a vertical gradient, where lower parts have higher pressure
### How Does Pressure Vary with Depth?
@@ -116,11 +114,11 @@ The -ve sign indicates that as $z$, height, increases, $p$, pressure, decreases.
### Absolute and Gauge Pressure
- Absolute Pressure is measured relative to zero (a vacuum)
- Guage pressure = absolute pressure - atmospheric pressure
- Gauge pressure = absolute pressure - atmospheric pressure
- Often used in industry
- If abs. pressure = 3 bar and atmospheric pressure is 1 bar, then gauge pressure = 2 bar
- If absolute pressure = 3 bar and atmospheric pressure is 1 bar, then gauge pressure = 2 bar
- Atmospheric pressure changes with altitude
## Compressibility
@@ -132,7 +130,7 @@ The -ve sign indicates that as $z$, height, increases, $p$, pressure, decreases.
## Surface Tension
- In a liquid, molecules are held together by molecular attraction
- At a boundry between two fluids this creates "surface tension"
- At a boundary between two fluids this creates "surface tension"
- Surface tension usually has the symbol $$\gamma$$
## Ideal Gas
@@ -155,7 +153,7 @@ The -ve sign indicates that as $z$, height, increases, $p$, pressure, decreases.
- Pressure always in Pa
- Temperature always in K
## Units and Dimentional Analysis
## Units and Dimensional Analysis
- It is usually better to use SI units
- If in doubt, DA can be useful to check that your answer makes sense
@@ -289,7 +287,7 @@ p_1 - p_2 &= \rho_wg(z_C-z_B-z_C+z_A) + \rho_mg\Delta z \\
the upper surface (figure 1.4). The tank and riser are filled with
water such that the water level in the riser pipe is 3.5 m above the
Calulate:
Calculate:
i. The gauge pressure at the base of the tank.
@@ -299,7 +297,7 @@ p_1 - p_2 &= \rho_wg(z_C-z_B-z_C+z_A) + \rho_mg\Delta z \\
> $$\rho gh = 1000\times9.81\times3.5 = 34 \text{ kPa}$$
iii. The force exercted on the base of the tank due to gauge water pressure.
iii. The force exerted on the base of the tank due to gauge water pressure.
> $$F = p\times A = 49\times10^3\times6\times3 = 8.8\times10^5 \text{ N}$$
@@ -345,7 +343,7 @@ p_1 - p_2 &= \rho_wg(z_C-z_B-z_C+z_A) + \rho_mg\Delta z \\
## Submerged Surfaces
### Prepatory Maths
### Preparatory Maths
#### Integration as Summation
@@ -370,7 +368,7 @@ Take the following lamina:
1. Split the lamina into elements parallel to the chosen axis
2. Each element has area $\delta A = w\delta y$
3. The moment of area ($\delta M$) of the element is $\delta Ay$
4. The sum of moments of all the elements is equal to the moment $M$ obtained by assuing all the
4. The sum of moments of all the elements is equal to the moment $M$ obtained by assuming all the
area is located at the centroid or:
$$Ay_c = \int_{area} \! y\,\mathrm{d}A$$
@@ -426,7 +424,7 @@ Determine the location of the centroid of a rectangular lamina.
</details>
### Horizontal Submereged Surfaces
### Horizontal Submerged Surfaces
![](./images/vimscrot-2021-10-20T10:33:16,783724117+01:00.png)
@@ -492,12 +490,12 @@ Where $\rho$ is the density of the fluid, and $V$ is the volume of displaced flu
### Immersed Bodies
As pressure increases with depth, the fluid exerts a resultant upward force on a body.
There is no horizontal component of the buoyancy force because the vertiscal projection of the body
There is no horizontal component of the buoyancy force because the vertical projection of the body
is the same in both directions.
### Rise, Sink, or Float?
- $F_B = W$ \rightarrow equilirbrium (floating)
- $F_B = W$ \rightarrow equilibrium (floating)
- $F_B > W$ \rightarrow body rises
- $F_B < W$ \rightarrow body sinks