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

測定の確実性は、測定の桁数と使用する機器の精度という2つの要素に依存します。
測定された量では、最後の不確定な数字を含むすべての数字は有効数字と呼ばれ、特定のルールを使用して決定できます。
ゼロ以外の数字とすべてのキャプティブ ゼロ (ゼロ以外の 2 桁の間にある) は重要です。たとえば、28 には 2 つの有効数字があり、26.25 には 4 つ、208 には 3 つの有効数字があります。
先行ゼロは小数点を特定するだけなので、決して重要ではありません。たとえば、0.00208 には 3 つの有効数字があります。このような量は、指数表記を使用して表すことができます。したがって、0.00208は10−3×2.08と書くことができます。
末尾のゼロは、10 進数形式の数値でのみ有効です。2200 には 2 つの末尾のゼロと 2 つの有効数字がありますが、2200.0 と 2200.1 にはどちらも 5 つの有効数字があります。
小数点のない数量の場合、末尾のゼロの意味はあいまいになります。したがって、2200 は、有効数字が 2 つの場合は 2.2 × 103、有効数字は 3 つの場合は 2.20 x 103 と記述できます。

有効数字のルール

Rules of Significant Figures

いかなる測定においても、測定ツールの精度は重要な要素です。 たとえば、通常の定規は、最も近いミリメートルまで長さを測定できます。 一方、ノギスは 0.01 mm 単位で長さを測定できます。 その結果、ノギスは非常に微細な長さの変化を測定できるため、より正確な測定ツールとなります。 測定ツールの精度が高ければ、測定値もより正確になります。

測定値を表す場合、最後の桁は測定者によって何らかの方法で計算されていることを強調しておく必要があります。 たとえば、棒の長さを定規で測っている人は、それが 13.2 cm から 13.3 cm の間にあることに気づき、最後の桁の値を推定する必要があります。 有効数字の規則は、測定値に記録される最後の桁が、ある程度の不確実性を伴う最初の桁であるということです。 左側の最初の測定値から始めて、右側に書かれた最後の桁までの桁数を数えて、値の有効桁数を決定します。 有効数字は、値の測定に使用される測定ツールの精度を表します。

本文は <a href="https://openstax.org/books/university-physics-volume-1/pages/1-6-significant-figures">< から引用しています。 Openstax、University Physics Volume 1, Section: 1.6 Significant Figures. </a>

どのような測定においても、測定ツールの精度は重要な要素です。たとえば、通常の定規は、最も近い長さを測定できます...

Education

JoVE Core

Mechanical Engineering

機械工学

Unit 1

ユニット1

Physics Basics

物理学の基礎

KEY TERMS AND CONCEPTS

主要用語と概念

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

counting-significant-figures-in-measurements

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rules of significant figures

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...

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key terms and concepts

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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