From 16555851b6514a736c5c9d8e73de7da7fc9b6288 Mon Sep 17 00:00:00 2001 From: Prefetch Date: Thu, 20 Oct 2022 18:25:31 +0200 Subject: Migrate from 'jekyll-katex' to 'kramdown-math-sskatex' --- source/know/concept/newtons-bucket/index.md | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) (limited to 'source/know/concept/newtons-bucket/index.md') diff --git a/source/know/concept/newtons-bucket/index.md b/source/know/concept/newtons-bucket/index.md index 757262d..21740b9 100644 --- a/source/know/concept/newtons-bucket/index.md +++ b/source/know/concept/newtons-bucket/index.md @@ -10,23 +10,23 @@ layout: "concept" --- **Newton's bucket** is a cylindrical bucket -that rotates at angular velocity $\omega$. +that rotates at angular velocity $$\omega$$. Due to [viscosity](/know/concept/viscosity/), any liquid in the bucket is affected by the rotation, -eventually achieving the exact same $\omega$. +eventually achieving the exact same $$\omega$$. However, once in equilibrium, the liquid's surface is not flat, but curved upwards from the center. -This is due to the centrifugal force $\va{F}_\mathrm{f} = m \va{f}$ on a molecule with mass $m$: +This is due to the centrifugal force $$\va{F}_\mathrm{f} = m \va{f}$$ on a molecule with mass $$m$$: $$\begin{aligned} \va{f} = \omega^2 \va{r} \end{aligned}$$ -Where $\va{r}$ is the molecule's position relative to the axis of rotation. +Where $$\va{r}$$ is the molecule's position relative to the axis of rotation. This (fictitious) force can be written as the gradient -of a potential $\Phi_\mathrm{f}$, such that $\va{f} = - \nabla \Phi_\mathrm{f}$: +of a potential $$\Phi_\mathrm{f}$$, such that $$\va{f} = - \nabla \Phi_\mathrm{f}$$: $$\begin{aligned} \Phi_\mathrm{f} @@ -34,8 +34,8 @@ $$\begin{aligned} = - \frac{\omega^2}{2} (x^2 + y^2) \end{aligned}$$ -In addition, each molecule feels a gravitational force $\va{F}_\mathrm{g} = m \va{g}$, -where $\va{g} = - \nabla \Phi_\mathrm{g}$: +In addition, each molecule feels a gravitational force $$\va{F}_\mathrm{g} = m \va{g}$$, +where $$\va{g} = - \nabla \Phi_\mathrm{g}$$: $$\begin{aligned} \Phi_\mathrm{g} @@ -43,7 +43,7 @@ $$\begin{aligned} \end{aligned}$$ Overall, the molecule therefore feels an "effective" force -with a potential $\Phi$ given by: +with a potential $$\Phi$$ given by: $$\begin{aligned} \Phi @@ -51,7 +51,7 @@ $$\begin{aligned} = \mathrm{g} z - \frac{\omega^2}{2} (x^2 + y^2) \end{aligned}$$ -At equilibrium, the [hydrostatic pressure](/know/concept/hydrostatic-pressure/) $p$ +At equilibrium, the [hydrostatic pressure](/know/concept/hydrostatic-pressure/) $$p$$ in the liquid is the one that satisfies: $$\begin{aligned} @@ -59,7 +59,7 @@ $$\begin{aligned} = - \nabla \Phi \end{aligned}$$ -Removing the gradients gives integration constants $p_0$ and $\Phi_0$, +Removing the gradients gives integration constants $$p_0$$ and $$\Phi_0$$, so the equilibrium equation is: $$\begin{aligned} @@ -67,16 +67,16 @@ $$\begin{aligned} = - \rho (\Phi - \Phi_0) \end{aligned}$$ -We isolate this for $p$ and rewrite $\Phi_0 = \mathrm{g} z_0$, -where $z_0$ is the liquid height at the center: +We isolate this for $$p$$ and rewrite $$\Phi_0 = \mathrm{g} z_0$$, +where $$z_0$$ is the liquid height at the center: $$\begin{aligned} p = p_0 - \rho \mathrm{g} (z - z_0) + \frac{\omega^2}{2} \rho (x^2 + y^2) \end{aligned}$$ -At the surface, we demand that $p = p_0$, where $p_0$ is the air pressure. -The $z$-coordinate at which this is satisfied is as follows, +At the surface, we demand that $$p = p_0$$, where $$p_0$$ is the air pressure. +The $$z$$-coordinate at which this is satisfied is as follows, telling us that the surface is parabolic: $$\begin{aligned} -- cgit v1.2.3