From bf4cdfb0778835465f97eb3ceaca9a6ec80a8a9a Mon Sep 17 00:00:00 2001 From: eggy Date: Sat, 7 Nov 2020 10:52:01 -0500 Subject: [PATCH] phys: add efficiency and power --- docs/sph3u7.md | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/docs/sph3u7.md b/docs/sph3u7.md index ce585f2..d4a51b0 100644 --- a/docs/sph3u7.md +++ b/docs/sph3u7.md @@ -470,6 +470,18 @@ $$\Sigma E_i = \Sigma E_f$$ The types of energy involved may have varying values as long as their sum is fixed. **Work** determines how energy is distributed among the types of energy. +### Power + +Power is a a scalar unit represented in **watts** ($\text{1 W}=\frac{\text{1 J}}{\text{1 s}}$), and it is **not energy**, but instead the work done over a time interval, or the rate of doing work. +$$P=\frac{\Delta E}{\Delta t}$$ + +### Efficiency + +Efficiency measures how much work, energy, or power is retained in a process, and is represented as a percentage ($1$ being 100% efficient, $0$ being 0% efficient). +$$\text{Efficiency = }\frac{\text{useful work/energy/power output}}{\text{total work/energy/power input}}$$ + +The second law of thermodynamics states that some energy is always lost to a non-useful form when converted, so the efficiency of a process is **always less than** $100%$. + ## 2.4 - Momentum and impulse ### Momentum