From e5f44d97c6652f262c82b5c796c07a7a22a00e90 Mon Sep 17 00:00:00 2001
From: Prefetch
Date: Sun, 4 Jul 2021 20:02:27 +0200
Subject: Expand knowledge base

---
 content/know/concept/lagrangian-mechanics/index.pdc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'content/know/concept/lagrangian-mechanics')

diff --git a/content/know/concept/lagrangian-mechanics/index.pdc b/content/know/concept/lagrangian-mechanics/index.pdc
index 24e1f93..dcf555b 100644
--- a/content/know/concept/lagrangian-mechanics/index.pdc
+++ b/content/know/concept/lagrangian-mechanics/index.pdc
@@ -4,6 +4,7 @@ firstLetter: "L"
 publishDate: 2021-07-01
 categories:
 - Physics
+- Classical mechanics
 
 date: 2021-07-01T18:44:43+02:00
 draft: false
@@ -16,7 +17,10 @@ markup: pandoc
 which is equivalent to Newton's laws,
 but offers some advantages.
 Its mathematical backbone is the
-[calculus of variations](/know/concept/calculus-of-variations/).
+[calculus of variations](/know/concept/calculus-of-variations/),
+and hence it is built on the **principle of least action**,
+which states that the path taken by a system
+will be a minimum of the **action** (i.e. energy cost) of that path.
 
 For a moving object with position $x(t)$ and velocity $\dot{x}(t)$,
 we define the Lagrangian $L$ as the difference
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