Name: measurement units, standards, and si basics
Uploaded: 2023-09-22T11:49:38.000Z
Duration: 1 min 10 s
Channel: JoVE

Une grandeur physique est un nombre qui décrit quantitativement un phénomène physique. Par exemple, la longueur est une grandeur physique qui décrit la distance entre deux points.
Les mesures des grandeurs physiques sont exprimées en termes d’unités. La masse de votre corps peut être exprimée en kilogrammes et votre taille en mètres.
Les grandeurs physiques exprimées sans unités standard sont difficiles à comprendre. Par exemple, si la hauteur de la Tour Eiffel est de 300, sans fournir d’unités, le contexte du nombre n’est pas clair. Cela signifie que la tour Eiffel peut être relativement haute ou très courte.
Afin de mesurer et de rapporter avec précision les différentes propriétés de la matière, un système commun de mesure a été développé, connu sous le nom de Système international d’unités ou unités SI.
Le système SI recommande d’utiliser sept grandeurs de base et leurs unités, qui forment le Système international de quantités.

unités et normes de mesure

Units and Standards of Measurement

Une quantité physique est définie soit par sa méthode de mesure, soit en précisant comment elle est calculée à partir d'autres mesures. Par exemple, considérons un cube métallique. Nous pourrions définir sa masse et ses dimensions en spécifiant des méthodes pour les mesurer, telles que l'utilisation d'une balance et d'une règle graduée. Ensuite, nous pourrions définir le volume en affirmant que c'est le cube de son côté, et nous pourrions calculer la densité en divisant la masse par le volume.

Les mesures de quantités physiques sont exprimées en termes d'unités, qui sont des valeurs standardisées. Par exemple, la longueur du côté d'un cube, qui est une quantité physique, peut être exprimée en unités de mètres ou de centimètres, selon la taille du cube.

Il existe principalement deux systèmes d'unités utilisés. Le premier est le système métrique, qui utilise des unités SI, et le second est le système coutumier ou impérial, qui utilise des unités anglaises. SI est l'abréviation internationale du Système international d'unités. C'est le système d'unités le plus largement utilisé dans le monde et il est considéré comme le système standard par les scientifiques et les mathématiciens.

Ce texte est adapté de <a href="https://openstax.org/books/university-physics-volume-1/pages/1-2-units-and-standards">Openstax, University Physics Volume 1, Section 1.2: Units and Standards.</a>

Unités et normes de mesure

Une grandeur physique est définie soit en spécifiant sa méthode de mesure, soit en indiquant comment elle est calculée à partir d’autres mesures. Par exemple...

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measurement units, standards, and si basics

Measurement units, standards, and SI basics help scientists describe physical quantities clearly. A unit gives a number meaning, while a standard provides a fixed reference for that measurement. Together, they make results easier to compare and understand.

The International System of Units, or SI, is the most common measurement system in science. It uses agreed-upon base units for common quantities. These standards reduce confusion when measurements are shared across labs, classrooms, and countries.

Using the same units and standards also makes data more reliable. It allows students and scientists to compare measurements and communicate results with less error. This foundation is essential for accurate work in physics, chemistry, and other sciences.

Measurement Units, Standards, and SI Basics

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units and standards of measurement

Measurement units, standards, and SI basics help scientists describe physical quantities clearly. A unit gives a number meaning, while a standard provides a fixed reference for that measurement. Together, they make results easier to compare and understand. The International System of Units, or SI, is the most common measurement system in science. It uses agreed-upon base units for common quantities. These standards reduce confusion when measurements are shared across labs, classrooms, and...

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key terms and concepts

Learn how measurement units, standards, and the SI system give physical quantities clear meaning and make scientific results easier to compare.

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Measurement Units, Standards, and SI Basics

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