Chapter 0
Physics Basics
Scalers 简介
Many familiar physical quantities can be specified completely by giving a single number and the appropriate unit. For example, "a class period lasts ...
向量或叉积
Vector multiplication of two vectors yields a vector product, with the magnitude equal to the product of the individual vectors multiplied by the sine of ...
向量简介
To define some physical quantities, there is a need to specify both magnitude as well as direction. For example, when the U.S. Coast Guard dispatches a ...
计量单位和标准
A physical quantity is defined either by specifying its measurement method or by stating how it is calculated from other measurements. For example, ...
准确度和精密度
Scientists typically make repeated measurements of a quantity to ensure the quality of their findings and to evaluate both the precision and the accuracy ...
有效数字规则
In any measurement, the precision of the measuring tool is an essential factor. An ordinary ruler, for example, can measure length to the closest ...
随机误差和系统误差
Scientists always try their best to record measurements with the utmost accuracy and precision. However, sometimes errors do occur. These errors can be ...
位置和位移
The position of an object defines its location relative to a convenient frame of reference at any particular time. A frame of reference is an arbitrary ...
位置和位移矢量
To describe the motion of an object, one should first be able to describe its position (where it is at any particular time). More precisely, the position ...
质量和重量
Mass and weight are often used interchangeably in everyday conversation. For example, medical records often show our weight in kilograms, but never ...
地球上重力引起的加速度
Newton's second law is closely related to his first law of motion. It mathematically gives the cause-and-effect relationship between force and changes ...
张力
Tension is a force along the length of a medium, in particular, a force carried by a flexible medium, such as a rope or cable. The word "tension" ...
引力
In the years before Newton, a general belief prevailed that different laws governed objects in the sky than objects on Earth. When Kepler wrote down the ...
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