牛頓運動定律

牛頓運動定律是經典力學的三條基礎定律，由牛頓在於1687年7月5日發表的巨著《自然哲學的數學原理》里提出。

通常的現代表述

• 第一定律：假若施加於某物體的外力為零，則該物體的運動速度不變（也稱慣性定律）。
• 第二定律：施加於物體的外力等於此物體的質量與加速度的乘積（也稱加速度定律）。
• 第三定律：當兩個物體相互作用於對方時，彼此施加於對方的力，其大小相等、方向相反（也稱作用力與反作用力定律）。

文言版

• 律一曰：靜者不自動，動者不自止；動路必直，速率必均。
• 律二曰：質量加速度積與物力相侔。
• 律三曰：施力必受反，值等而向反。

拉丁語原文

• Lex. I. Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressis cogitur statum illum mutare.
• Lex. II. Mutationem motus proportionalem esse vi motrici impressæ, & fieri secundum lineam rectam qua vis illa imprimitur.
• Lex. III. Actioni contrariam semper & æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse æquales & in partes contrarias dirigi.

英文譯文

• LAW I. Every body perseveres in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed thereon.
• LAW II. The alteration of motion is ever proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed.
• LAW III. To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.