Name: torque on a flywheel: direction and size
Uploaded: 2023-09-22T11:49:20.000Z
Duration: 1 min 18 s
Channel: JoVE

Le couple, ou le moment d’une force, est la capacité d’une force à faire tourner un corps autour d’un point ou d’un axe qui n’est pas dans la ligne d’action de la force. Il s’agit d’une quantité vectorielle.
Prenons l’exemple d’un volant d’inertie, où une force est appliquée pour faire tourner le volant autour du point O.
Ici, le bras de moment est la distance perpendiculaire entre le point O et la ligne d’action de la force.
L’intensité de la force est multipliée par le bras de moment pour obtenir l’intensité du moment. Ainsi, l’unité du moment d’une force est le newton-mètre.
Son amplitude est maximale lorsque la force appliquée est tangente au volant.
La règle de la main droite est utilisée pour déterminer la direction du moment. Si les doigts recourbés représentent la rotation provoquée par le moment, alors le pouce représente la direction du moment.
Conventionnellement, le moment positif désigne la rotation dans le sens inverse des aiguilles d’une montre, tandis que le signe négatif désigne la rotation dans le sens des aiguilles d’une montre du volant.

<ol>
	<li>Hibbeler, R.C. (2016). Génie mécanique \u2012 Statique et dynamique. Hoboken, New Jersey : Pearson Prentice Hall. pp 121 à 122.</li>
</ol>

moment d'une force : formulation scalaire

Le moment d'une force, également connu sous le nom de couple, mesure la capacité de la force à créer un mouvement de rotation dans un corps autour d'un axe. C'est une grandeur vectorielle, ce qui signifie qu'elle a à la fois une magnitude et une direction. Ce concept est largement utilisé en ingénierie, en physique et en mécanique. Considérons un exemple simple d'une roue à aubes en rotation autour d'un point, O, en appliquant une force sur celle-ci. Dans ce cas, le bras de levier est la distance perpendiculaire entre le point O et la ligne d'action de la force. La magnitude du moment est calculée en multipliant la magnitude de la force par le bras de levier. Cette grandeur a l'unité de newton-mètre (Nm). Le moment maximal se produit lorsque la force appliquée est tangentielle à la roue à aubes, car elle est perpendiculaire au rayon de la roue à aubes. La magnitude du moment augmente également avec la magnitude de la force appliquée et la longueur du bras de levier. La règle de la main droite détermine la direction du moment. Si les doigts de la main droite bouclent dans le sens du mouvement de rotation produit par le moment, alors le pouce pointe dans la direction du moment. Conventionnellement, un moment positif indique un mouvement de rotation dans le sens inverse des aiguilles d'une montre, tandis qu'un signe négatif indique un mouvement de rotation dans le sens des aiguilles d'une montre. Le moment d'une force est essentiel pour comprendre la dynamique des machines et des structures. C'est un outil essentiel pour analyser et prédire le comportement des systèmes mécaniques complexes.

Moment d'une force : Formulation scalaire

Le moment d’une force, également connu sous le nom de couple, mesure la capacité de la force à créer un mouvement de rotation dans un corps autour d’un axe. Il s’agit d’un vecteur...

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Moment of a Force: Scalar Formulation

torque on a flywheel: direction and size

Torque, or the moment of a force, describes how a force can make an object turn about an axis. It is a vector quantity, so it has both size and direction. This idea is important in physics, mechanics, and engineering.

A simple flywheel example shows how torque works. The flywheel rotates about point O when a force is applied to it. The moment arm is the perpendicular distance from point O to the line of action of the force. The moment, in newton-meter (N-m), is found by multiplying the force by the moment arm.

The largest moment happens when the force acts tangentially to the flywheel. In that case, the force is perpendicular to the radius of the flywheel. The moment also gets larger when the applied force is larger or when the moment arm is longer.

The right-hand rule gives the direction of the moment. If the fingers of the right hand curl in the direction of the rotation, the thumb points along the moment direction. By convention, counterclockwise motion is positive, and clockwise motion is negative. This helps in analyzing machines and structures and in predicting how mechanical systems behave.

Torque on a Flywheel: Direction and Size

moment of a force: scalar formulation

Torque, or the moment of a force, describes how a force can make an object turn about an axis. It is a vector quantity, so it has both size and direction. This idea is important in physics, mechanics, and engineering. A simple flywheel example shows how torque works. The flywheel rotates about point O when a force is applied to it. The moment arm is the perpendicular distance from point O to the line of action of the force. The moment, in newton-meter (N-m), is found by multiplying the force...

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key terms and concepts

Learn how torque, or moment of a force, depends on force size, moment arm length, and direction using a flywheel example and the right-hand rule.

Torque on a Flywheel: Direction and Size | JoVE K12

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Torque on a Flywheel: Direction and Size

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