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。

Velocity

速度

The average speed of an object is defined as the distance traveled divided by the time elapsed. Velocity is a vector quantity, and average velocity can be defined as the displacement divided by the time. For the special case of straight line motion in the x direction, the average velocity takes the form:

物体的平均速率定义为物体行进的路程除以所用的时间。速度是一个矢量量，平均速度可以定义为位移除以时间。对于沿x方向直线运动的特殊情况，平均速度的形式为：

The units for velocity can be implied from the definition to be meters/second or in general any distance unit over any time unit.

速度的单位可以从定义中推断出来，应为米/秒，或一般地说任何距离单位除以任何时间单位。

You can approach an expression for the instantaneous velocity at any point on the path by taking the limit as the time interval gets smaller and smaller. Such a limiting process is called a derivative and the instantaneous velocity can be defined as

你可以通过让时间间隔越来越小，来得到路径上任意一点的瞬时速度的表达式。这种极限过程称为导数，瞬时速度可以定义为
Average velocity, straight line motion
平均速度，直线运动
 Average velocity, general case
平均速度（一般情况）
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Average Velocity, Straight Line

平均速度，直线运动
The average speed of an object is defined as the distance traveled divided by the time elapsed. Velocity is a vector quantity, and average velocity can be defined as the displacement divided by the time. For the special case of straight line motion in the x direction, the average velocity takes the form:
If the beginning and ending velocities for this motion are known, and the acceleration is constant, the average velocity can also be expressed as
For this special case, these expressions give the same result.

Example for non-constant acceleration

非恒定加速度的例子
物体的平均速率定义为物体经过的路程除以时间间隔。速度是一个矢量量，平均速度可以定义为位移除以时间。对于沿x方向直线运动的特殊情况，平均速度的形式为：如果已知这段运动的初速度和末速度，并且加速度恒定，则平均速度也可以表示为。对于这种特殊情况，这些表达式给出相同的结果。
 Index

Motion concepts
索引运动概念
 
HyperPhysics***** Mechanics
力学
R Nave
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Average Velocity, General

平均速度，一般情况
The average speed of an object is defined as the distance traveled divided by the time elapsed. Velocity is a vector quantity, and average velocity can be defined as the displacement divided by the time. For general cases involving non-constant acceleration, this definition must be applied directly because the straight line average velocity expressions do not work.
If the positions of the initial and final points are known, then the distance relationship can be used to find the displacement.
物体的平均速率定义为物体经过的路程除以所用的时间。速度是一个矢量量，平均速度可以定义为位移除以时间。对于一般非恒定加速度的情况，必须直接应用这个定义，因为直线平均速度的表达式不适用。如果初始点和终点的位置已知，就可以利用距离关系来求出位移。
 Index

Motion concepts
索引运动概念
 
HyperPhysics***** Mechanics
力学
R Nave
 Go Back
返回