Name: using vectors to describe motion
Uploaded: 2023-09-22T11:49:39.000Z
Duration: 1 min
Channel: JoVE

Considérez une mouche en mouvement. Pour localiser sa position dans un espace tridimensionnel, un système de coordonnées cartésiennes est utilisé, et les vecteurs unitaires le long de l’axe fournissent sa direction.
La flèche vectorielle qui s'étend de l'origine à l'emplacement de l'objet est le vecteur de position. Il peut être représenté en termes de vecteurs unitaires.
Le vecteur position est la somme des composantes vectorielles sur chaque axe et leurs normes fournissent la position le long de chaque axe.
Si la mouche continue son mouvement, son vecteur de position change, et la différence de vecteur entre les vecteurs de position est appelée le vecteur de déplacement, Δr, qui représente le changement de position.
Par exemple, si la mouche est au point A, et qu’après le temps t, elle atteint le point B, alors en utilisant les vecteurs position de A et B, le vecteur de déplacement de la mouche pour le temps t peut être obtenu.

vecteurs de position et de déplacement

Pour décrire le mouvement d'un objet, il faut d'abord être capable de décrire sa position (c’est-à-dire là où il se trouve à un moment donné). Plus précisément, la position doit être spécifiée par rapport à un cadre de référence pratique. Un cadre de référence est un ensemble arbitraire d'axes à partir desquels la position et le mouvement d'un objet sont décrits. La Terre est souvent utilisée comme cadre de référence pour décrire la position d'un objet par rapport aux objets stationnaires sur Terre.

De plus, plusieurs types importants de mouvement se déroulent uniquement dans deux dimensions, c'est-à-dire dans un plan. Ces mouvements peuvent être décrits par deux composantes de position, de vélocité et d'accélération. Si un objet se déplace par rapport à un cadre de référence, alors la position de l'objet change ; ce changement de position est appelé déplacement. Le mot déplacement implique qu'un objet a bougé ou a été déplacé. Étant donné que le déplacement indique une direction, il s'agit d'un vecteur et peut être soit positif, soit négatif, en fonction du choix de la direction. De plus, une analyse du mouvement peut comporter de nombreux déplacements incorporés, et de nombreuses applications en physique peuvent comporter une série de déplacements. Ainsi, le déplacement total est la somme des déplacements individuels, qui doivent être évalués avec soin en utilisant l'addition vectorielle.

Ce texte est adapté de <a href="https://openstax.org/books/university-physics-volume-1/pages/4-1-displacement-and-velocity-vectors">Openstax, University Physics Volume 1, Section 4:1 Displacement and Velocity Vectors.</a>

Vecteurs de position et de déplacement

Pour décrire le mouvement d’un objet, il faut d’abord être capable de décrire sa position (où il se trouve à un moment donné). Plus précisément, la position ...

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Position and Displacement Vectors

using vectors to describe motion

Position and displacement vectors describe motion in physics. A position vector shows where an object is located relative to a chosen origin. A displacement vector shows how far and in what direction the object moves from one point to another.

These vectors are useful because they give a clear way to track movement in space. The video connects position and displacement to the idea of a reference point and shows how direction matters as much as distance. That makes them important for describing motion in one, two, or three dimensions.

The lesson also shows how to represent these vectors using arrows and coordinate systems. By comparing the starting point and ending point, students can see the difference between an object’s location and its change in position. This helps build the foundation for later topics in kinematics.

Using Vectors to Describe Motion

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Vectors describe quantities that have both size and direction. They are used in physics to show how motion, force, and other quantities act in space. A vector can be represented with an arrow. The length of the arrow shows the size, and the arrowhead shows the direction. This makes vectors useful for comparing how one quantity points relative to another. Scalars are different because they have size only and no direction. Understanding the difference between vectors and scalars is an important...

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position and displacement

Tracking Motion with Position and Displacement

Position and displacement are key ideas in straight-line motion. Position tells where an object is located compared with a chosen starting point, called the origin. Displacement describes how far and in what direction the object has moved from its starting position. These ideas help describe motion clearly. Position can change as an object moves. Displacement focuses on the change in position, not just the path taken. That makes it useful for comparing motion in a simple and precise way.

position and displacement vectors

Position and displacement vectors describe motion in physics. A position vector shows where an object is located relative to a chosen origin. A displacement vector shows how far and in what direction the object moves from one point to another. These vectors are useful because they give a clear way to track movement in space. The video connects position and displacement to the idea of a reference point and shows how direction matters as much as distance. That makes them important for describing...

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key terms and concepts

Learn how position vectors and displacement vectors describe an object’s location and movement in 1D, 2D, and 3D using arrows and coordinates.

Using Vectors to Describe Motion | JoVE K12

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Using Vectors to Describe Motion

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