Name: counting significant figures in measurements
Uploaded: 2023-09-22T11:49:39.000Z
Duration: 1 min 44 s
Channel: JoVE

测量的确定性取决于两个因素：测量值的有效数字位数以及所用仪器的精度。
在测量值中，所有数字（包括最后一位不确定的数字）都称为有效数字，可通过特定规则确定。
所有非零数字以及位于两个非零数字之间的夹心零均为有效数字。例如，28 有两位有效数字，26.25 有四位，而 208 有三位。
前导零从不视为有效数字，因为它们仅用于确定小数点的位置。例如，0.00208 有三位有效数字。这类数值可以用指数形式表示。因此，0.00208 可以写作 2.08 × 10−3。
只有在十进制格式的数字中，末尾的零才具有有效数字意义。2200 有两个末尾零，但仅有两个有效数字；而 2200.0 和 2200.1 均有五个有效数字。
对于没有小数点的数值，末尾零的有效性会变得不明确。因此，2200 可以写成具有两位有效数字的 2.2 × 103，或写成具有三位有效数字的 2.20 ×&#160;103。

有效数字的规则

Rules of Significant Figures

在任何测量中，测量工具的精度都是一个重要因素。 例如，普通的尺子可以测量精确到毫米的长度； 另一方面，卡尺可以测量精确到 0.01 毫米的长度。 因此，卡尺是一种更精确的测量工具，因为它可以测量极其微小的长度变化。 测量工具越精密，测量就越准确。 应该强调的是，当我们表示测量值时，最后一位数字是由测量者以某种方式计算出来的。 例如，一个人用尺子测量一根棍子的长度，发现它看起来在 13.2 厘米到 13.3 厘米之间，因此他们必须估计最后一位数字的值。 有效数字的规则是，测量值中写下的最后一位数字是具有一定不确定性的第一位数字。 从左侧的第一个测量值开始，计算到右侧写入的最后一位数字的位数，以确定值中的有效位数。 有效数字代表用于测量值的测量工具的精度。 文本采用<a href="https://openstax.org/books/university-physics-volume-1/pages/1-6-significant-figures"> Openstax，大学物理第 1 卷，第：1.6 有效数字。</a>

在任何测量中，测量工具的精度都是一个关键因素。例如，普通直尺可以将长度测量到最接近的……

Education

教育

JoVE Core

Mechanical Engineering

机械工程

Unit 1

第一单元

Physics Basics

物理基础

KEY TERMS AND CONCEPTS

关键术语与概念

有效数字规则

counting significant figures in measurements

Significant figures help students record measurements with the correct level of precision. They show which digits in a number are meaningful and which only help place the decimal point. In science class, this idea matters when writing and comparing measured values.

The rules for significant figures explain how to count these digits in different numbers. Some digits are always counted, while others depend on where they appear in the number. Learning the rules makes it easier to report answers clearly and consistently.

This topic is especially useful in physics and other measurement-based science work. It helps students decide how many digits to keep when writing results from lab work or calculations. That makes numerical answers easier to interpret and compare.

Counting Significant Figures in Measurements

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rules of significant figures

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Learn how to count significant figures in measurements and report scientific values with the right precision for high school science and lab work.

Counting Significant Figures in Measurements | JoVE K12

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mechanical engineering

Counting Significant Figures in Measurements

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