Bilingual edition: English is preserved and Chinese follows each unit. Terminology uses the confirmed v20260916 glossary; automated semantic review remains traceable.
中英双语版：英文原文完整保留，中文紧随对应单元；术语采用 v20260916 确认表，自动语义审校结果可追溯。

Physical Units

物理单位

Mechanics is the branch of physics in which the basic physical units are developed. The logical sequence is from the description of motion to the causes of motion (forces and torques) and then to the action of forces and torques. The basic mechanical units are those of

力学是物理学的一个分支，其中基本物理单位得以发展。逻辑顺序是从对运动的描述到运动的原因（力和力矩），然后到力和力矩的作用。基本机械单位是那些

All mechanical quantities can be expressed in terms of these three quantities. The standard units are the Systeme Internationale or SI units. The primary SI units for mechanics are the kilogram (mass), the meter (length) and the second (time). However if the units for these quantities in any consistent set of units are denoted by M, L, and T, then the scheme of mechanical relationships can be sketched out.

所有力学量都可以用这三个量来表示。标准单位是国际单位制（SI单位）。力学的主SI单位是千克（质量）、米（长度）和秒（时间）。然而，如果在任何一致的单位集中，这些量的单位分别用M、L和T表示，那么力学关系的方案就可以被勾勒出来。
Chain of mechanical quantities
机械量的连锁
 Development of mechanical units
机械单位的制定
 Table of units
单位表
 Unit conversions
单位换算
Comment on significant digits
评论有效数字
 Dimensional analysis
量纲分析
Motion to Energy
运动转化为能量
A brief overview of time.
时间的简要概述。
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This is an active graphic. Click on any segment for further information.
Motion to Energy
运动转化为能量
这是一个动态图形。点击任意一段获取更多信息。
 Index

Physical units
索引 物理单位
 
HyperPhysics***** Mechanics
力学
R Nave
 Go Back
返回





This is an active graphic. Click on any segment for further information.
Motion to Energy
运动转化为能量
这是一个动态图形。点击任意一段获取更多信息。
 Index

Physical units
索引 物理单位
 
HyperPhysics***** Mechanics
力学
R Nave
 Go Back
返回





Index

Physical units
索引 物理单位
 
HyperPhysics***** Mechanics
力学
R Nave
 Go Back
返回





Dimensional Analysis

量纲分析

Having the same units on both sides of an equation does not gaurantee that the equation is correct, but having different units on the two sides of an equation certainly gaurantees that it is wrong! So it is good practice to reconcile units in problem solving as one check on the consistency of the work. Units obey the same algebraic rules as numbers, so they can serve as one diagnostic tool to check your problem solutions.

方程两边具有相同的单位并不保证方程是正确的，但两边单位不同的方程肯定是错误的！因此，在问题求解中 reconciling 单位是一个检查工作一致性的好做法。单位遵循与数字相同的代数规则，因此可以作为检查问题解的一个诊断工具。

For example, in the solution for distance in constant acceleration motion, the distance is set equal to an expression involving combinations of distance, time, velocity and acceleration. But the combination of the units in each of the terms must yield just the unit of distance, since the left hand side of the equation has the dimension of distance.

例如，在恒定加速度运动的距离解中，距离被设定为一个包含距离、时间、速度和加速度的组合的表达式。但每个项中的单位组合必须仅产生距离的单位，因为方程左边的维度是距离。

Combinations of units pervade all of physics, and doing some analysis of the units is common practice. For example, in the case of centripetal force, it is not immediately evident that the quantity on the right has the dimensions of force, but it must. Checking it out:

物理的单位组合贯穿物理学的各个方面，对单位进行分析是常见的做法。例如，在向心力的情况下，右边的量是否具有力的量纲并不 immediately 明显，但必须如此。检查一下：

Often the use of dimensional analysis can be helpful as a reminder of what specialized units contain. In the case of the magnetic force on a moving charge, the magnetic field unit is a Tesla. But what is a Tesla? Checking out the force equation can remind you of the combination of basic units that is contained in the unit named a Tesla.

通常，用维度分析可以作为提醒，帮助我们了解特殊单位包含哪些基本单位。在磁力作用于运动电荷的情况下，磁场的单位是特斯拉。但什么是特斯拉呢？查阅力的公式可以提醒你，特斯拉这个名称所包含的基本单位组合。
 Index

Physical units
索引 物理单位
 
HyperPhysics***** Mechanics
力学
R Nave
 Go Back
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