From 3a0f79f2ce5c8450402235210405371ceb880058 Mon Sep 17 00:00:00 2001 From: Krishna Date: Sun, 22 Sep 2024 16:12:48 -0500 Subject: [PATCH] bouyancy --- content/physics/Forces.md | 48 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/content/physics/Forces.md b/content/physics/Forces.md index 803c7bf..49174f4 100644 --- a/content/physics/Forces.md +++ b/content/physics/Forces.md @@ -160,6 +160,54 @@ $$ k=\frac{||\vec{F}||}{x} $$ +# Buoyancy + +![](https://openstax.org/apps/archive/20240812.170248/resources/890168a9ef96d6cdea88cf7a401fd7bd9618187a) + +As shown in the image here, $||\vec{F}_B||$ is not simply equivalent to the weight (that's a force incorporating the force experienced because of gravity). Therefore, it's important to remember the more complicated formulas: + +$$ +F_1=h_1\rho gA +$$ +$$ +F_2=h_2\rho gA +$$ +And the total magnitude of the buoyant force is simply the subtraction of the force pushing the object up and the force pushing the object down: $F_B=F_2-F_1$. Breaking apart these equations, it's important to understand a couple things: + +- $\rho$, pronounced *rho* (the *h* is silent) is the density of the fluid. The SI unit for density is $\frac{\mathrm{kg}}{\mathrm{m}^3}$ +- *Standard Temperature and Pressure* (STP) is the state of a system at $273.15$ K or $0\degree$ C, at $10^5$ ($1$ bar/$14$ atm) of pressure. +- At STP, the density of water, $\rho_w=0.9982071\approx 1$ g/ml +- A liter is a measure of volume equivalent to $0.001$ cubic meters, or 1000 cubic centimeters. +- $A$ is the cross sectional area of the object where the object is not parallel to the static particles of the liquid + +> **Archimedes' Principle** \ +> $F_B=w_{\mathrm{fl}}$, but you often need to break this down to really be able to calculate what's required. + +## Fraction Submerged + +The fraction of an object submerged can easily be found using the following equation: + +$$ +\frac{V_{\mathrm{sub}}}{V_{\mathrm{obj}}}=\frac{V_{\mathrm{fl}}}{V_{\mathrm{obj}}} +$$ + +$V_{\mathrm{fl}}$ is the volume of fluid displaced, not the volume of fluid total. +$$ +\frac{V_{\mathrm{fl}}}{V_{\mathrm{obj}}}=\frac{m_{\mathrm{fl}}/\rho_{\mathrm{fl}}}{m_{\mathrm{obj}}/\rho_{\mathrm{obj}}} +$$ + +The following is only true if the object floats: +$$ +\frac{V_{\mathrm{fl}}}{V_{\mathrm{obj}}}=\frac{\rho_\mathrm{obj}}{\rho_\mathrm{fl}} +$$ + +# Circular motion + +**TODO!** + + + + [^1]: I'm working in radians here. [^2]: This is latin.