Name: newton's first law and reference frames
Uploaded: 2023-04-30T10:54:21.000Z
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Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Physical Science

Forces and Interactions

3.2.9-12.J

Inertial Frames of Reference

Le cadre de référence dans lequel les lois de Newton sont valides est appelé cadre de référence inertiel. L’objet par rapport à ce cadre de référence continue de rester au repos ou de se déplacer avec une vitesse constante.
Imaginons une voiture en mouvement. Le passager se déplace avec la voiture par rapport à la Terre. Lorsque la voiture s’arrête soudainement, la passagère subit une poussée vers l’avant alors qu’aucune force nette n’agit sur elle.
Bien que le passager avance par rapport à la voiture, sa vitesse par rapport à la Terre est maintenue.
L'inertie du passager tend à maintenir sa vitesse par rapport à la Terre en raison de la première loi du mouvement de Newton. Ici, le cadre de référence attaché à la Terre peut être considéré comme un cadre de référence inertiel.
Même si la vitesse de la Terre n'est pas constante en raison de sa rotation et de sa révolution, elle peut être considérée comme un référentiel inertiel car ses effets sont négligeables sur le mouvement des objets à la surface de la Terre.

Aucun conflit d’intérêts n’a été déclaré.

cadres de référence inertiels

La première loi de Newton est généralement considérée comme une déclaration sur les cadres de référence. Elle fournit une méthode pour identifier un type spécial de cadre de référence : le cadre de référence inertiel. En principe, nous pouvons rendre nulle la force nette sur un corps. Si sa vitesse par rapport à un cadre donné est constante, alors ce cadre est dit inertiel. Ainsi, par définition, un cadre de référence inertiel est un cadre de référence où la première loi de Newton est valable. La première loi de Newton s'applique aux objets ayant une vélocité constante. À partir de ce fait, nous pouvons déduire ce qui suit :

Un cadre de référence se déplaçant à une vélocité constante par rapport à un cadre inertiel est également inertiel.

Les cadres inertiels sont-ils courants dans la nature ? Il s'avère que, compte tenu des erreurs expérimentales, un cadre de référence au repos par rapport aux étoiles les plus lointaines ou « fixes » est inertiel. Tous les cadres se déplaçant de manière uniforme par rapport à ce cadre d'étoiles fixes sont également inertiels. Par exemple, un cadre de référence non-rotatif attaché au Soleil est, à toutes fins pratiques, inertiel car sa vitesse par rapport aux étoiles fixes ne varie pas de plus d'une partie sur 1010. La Terre accélère par rapport aux étoiles fixes car elle tourne sur son axe et gravite autour du Soleil ; par conséquent, un cadre de référence attaché à sa surface n'est pas inertiel. Pour la plupart des problèmes, un tel cadre sert cependant d'approximation suffisamment précise à un cadre inertiel car l'accélération d'un point à la surface de la Terre par rapport aux étoiles fixes est relativement faible (< 3,4 x 10-2 m/s2). Ainsi, nous considérons que les cadres de référence fixés sur la Terre sont inertiels, sauf indication contraire. Enfin, aucun cadre inertiel particulier n'est plus spécial qu'un autre. En ce qui concerne les lois de la nature, tous les cadres inertiels sont équivalents. Lors de l'analyse d'un problème, nous choisissons un cadre inertiel plutôt qu'un autre simplement pour des raisons de commodité.

Ce texte est adapté de <a href="https://openstax.org/books/university-physics-volume-1/pages/5-2-newtons-first-law">Openstax, University Physics Volume 1, Section 5.2: Newton's First Law.</a>

Cadres de référence inertiels

La première loi de Newton est généralement considérée comme une affirmation sur les cadres de référence. Il fournit une méthode pour identifier un type particulier de référence ...

Education

Enseignement

JoVE Core

Physics

Physique

Unit 1

Unité 1

Newton's Laws of Motion

Les lois du mouvement de Newton

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

newton's first law and reference frames

Newton's first law helps identify inertial reference frames. An inertial reference frame is one in which Newton's first law holds true. In that frame, an object with no net force moves at constant velocity.

A key idea is that any frame moving at constant velocity relative to an inertial frame is also inertial. For that reason, inertial frames can be found by comparing motion from one frame to another. The laws of physics do not give one inertial frame special status over another.

In nature, a frame at rest relative to the most distant fixed stars is inertial within experimental error. Any frame moving uniformly with respect to that fixed-star frame is also inertial. A non-rotating frame attached to the Sun is, for practical purposes, inertial because its velocity relative to the fixed stars changes by less than one part in 10^10.

A frame attached to Earth's surface is not truly inertial because Earth rotates on its axis and revolves around the Sun. Even so, the acceleration of a point on Earth's surface relative to the fixed stars is small, less than 3.4 x 10^-2 m/s^2. That is why Earth-fixed frames are usually treated as inertial unless stated otherwise.

Newton's First Law and Reference Frames

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Newton's First Law and Reference Frames | JoVE K12

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JoVE Core Physique présente plusieurs branches de la physique fondamentale grâce à des vidéos animées concises et faciles à comprendre ; cela inclut: la cinématique, la dynamique, la mécanique des fluides, la mécanique statique, les ondes et l'acoustique. En parallèle, les vidéos de scientifiques à l'action démontrent l'application de concepts associés à ces domaines dans des expériences de recherche classiques et originales réalisées dans des laboratoires modernes du monde entier.

Louisiana Student Standards for Science

High School

motion-and-stability-forces-and-interactions

Motion And Stability: Forces And Interactions

HS-PS2-2

HS-PS2-3

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Forces And Motion

Motion

Tennessee Academic Standards

Motion and Stability: Forces and Interactions

PHYS.PS2.14

Virginia  Standards of Learning

HIgh School

PS.8

PS.8.b

PH.3

PH.3.a

Next Generation Science Standards

Florida Department of Education

SC.912.P.12

SC.912.P.12.3

SC.912.P.12.8

SC.912.P.12.9

Texas Essential Knowledge and Skills

PHYS.5

PHYS.5.C

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Forces and Interactions

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3.2.9-12.M

Newton's First Law and Reference Frames

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