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

A certeza da medição depende de dois fatores: o número de dígitos na medição e a precisão do instrumento utilizado.
Em uma quantidade medida, todos os dígitos, incluindo o último dígito incerto, são chamados de algarismos significativos - e podem ser determinados usando regras específicas.
Quaisquer dígitos diferentes de zero e todos os zeros cativos - que ficam entre dois dígitos diferentes de zero - são significativos. Por exemplo, 28 tem dois algarismos significativos, enquanto 26,25 tem quatro e 208 tem três.
Os zeros à esquerda nunca são significativos, pois apenas localizam o ponto decimal. Por exemplo, 0,00208 tem três algarismos significativos. Tais quantidades podem ser expressas usando notações exponenciais. Assim, 0,00208 pode ser escrito como 2,08 × 10−3.
Os zeros à direita são significativos apenas em números formatados com decimal. 2200 tem dois zeros à direita e dois algarismos significativos, enquanto 2200.0 e 2200.1 têm 5 algarismos significativos.
Para quantidades sem pontos decimais, o significado dos zeros à direita torna-se ambíguo. Assim, 2200 pode ser escrito como 2,2 × 103 com dois algarismos significativos ou 2,20 x 103 com três algarismos significativos.

regras de algarismos significativos

Rules of Significant Figures

Em qualquer medição, a precisão da ferramenta de medição é um fator essencial. Uma régua comum, por exemplo, pode medir comprimentos até o milímetro mais próximo; um paquímetro, por outro lado, pode medir comprimentos até o centésimo de milímetro mais próximo. Como resultado, o paquímetro é uma ferramenta de medição mais precisa, pois pode medir mudanças extremamente pequenas no comprimento. As medidas serão mais exatas se a ferramenta de medição for mais precisa.

Deve-se enfatizar que, ao representarmos valores medidos, o último dígito foi calculado de alguma forma pela pessoa que fez a medição. Por exemplo, uma pessoa que mede o comprimento de um bastão com uma régua percebe que ele parece estar entre 13,2 cm e 13,3 cm e, portanto, deve estimar o valor do último dígito. A regra dos algarismos significativos é que o último dígito anotado em uma medida é o primeiro dígito com alguma incerteza. Comece com o primeiro valor medido à esquerda e conte o número de dígitos até o último dígito escrito à direita para determinar o número de algarismos significativos em um valor. Os algarismos significativos representam a precisão da ferramenta de medição usada para medir um valor.

Este texto foi adapatado de <a href="https://openstax.org/books/university-physics-volume-1/pages/1-6-significant-figures">Openstax, University Physics Volume 1, Section: 1.6 Significant Figures. </a>

Regras de Algarismos Significativos

Em qualquer medição, a precisão do instrumento de medição é um fator essencial. Uma régua comum, por exemplo, pode medir o comprimento até o mais próximo ...

Education

JoVE Core

Mechanical Engineering

Engenharia Mecânica

Unit 1

Unidade 1

Physics Basics

Fundamentos da Física

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

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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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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Counting Significant Figures in Measurements

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