動量

動量（粵拼：dung6 loeng6 | 英文：momentummou6 men1 tam4）係經典力學入面指物體嘅質量同速度嘅乘積。

定義

喺經典力學入面，線性動量，數學符號係 $\mathbf {p}$ ，指係一件物體嘅質量同佢速度乘埋得出嘅數^[1]^[2]：

\mathbf {p} =m\mathbf {v}

，當中

m

係件物體嘅質量。

動量有以下嘅特性：動量同速度一樣係向量，有方向同數值，喺國際單位制（SI Units）嗰度嘅單位係公斤米每秒－公斤（質量嘅單位）同米每秒（速度嘅單位）乘埋；用日常用語講嘅話，動量表達咗一件物體撞落去第啲嘢嗰陣，會有幾能夠引致後者嘅郁動有所改變－假設有一個檯波，佢以一定嘅速度撞落去第個檯波嗰度，假設第啲因素不變，如果前者嘅速度愈快或者質量愈大（兩者都可以引致動量上升），噉後者俾佢撞完之後嘅郁動嘅改變幅度會愈大^[3]。

根據動量守恆定律（conservation of momentum），喺一個封閉系統（唔能夠由外界攞動量）入面，所有物體嘅動量嘅總和永遠都唔會變－如果有嚿物體撞落去一嚿本嚟唔郁嘅嘢嗰度嘅話，後者會吸收動量並且加速，而前者實會少咗啲動量而減速－碰撞呢家嘢本質上可以想像成「動量嘅轉移」^[4]。

睇埋

牛頓第一定律

引述

↑ Goldstein, Herbert (1980). Classical mechanics (2nd ed.). Reading, Mass.: Addison-Wesley Pub. Co.
↑ The Physics Classroom - Momentum.
↑ Feynman, Richard P.; Leighton, Robert B.; Sands, Matthew (2005). The Feynman lectures on physics, Volume 1: Mainly Mechanics, Radiation, and Heat (Definitive ed.). San Francisco: Pearson Addison-Wesley. Ch. 9.
↑ Lanczos, Cornelius (1970). The Variational Principles of Mechanics. Toronto: University of Toronto Press.

拎

Conservation of momentum – A chapter from an online textbook

呢篇同物理相關係楔位文。歡迎幫維基百科擴寫佢。

[1] Goldstein, Herbert (1980). Classical mechanics (2nd ed.). Reading, Mass.: Addison-Wesley Pub. Co.

[2] The Physics Classroom - Momentum.

[3] Feynman, Richard P.; Leighton, Robert B.; Sands, Matthew (2005). The Feynman lectures on physics, Volume 1: Mainly Mechanics, Radiation, and Heat (Definitive ed.). San Francisco: Pearson Addison-Wesley. Ch. 9.

[4] Lanczos, Cornelius (1970). The Variational Principles of Mechanics. Toronto: University of Toronto Press.

[1]

[2]

[3]

[4]