Name: resolving forces in moment calculations
Uploaded: 2023-09-22T11:49:21.000Z
Duration: 1 min 20 s
Channel: JoVE

Le principe des moments, ou théorème de Varignon, décrit l'équilibre d'un corps rigide sous l'action de forces.
Il stipule que le moment d’une force autour d’un point est égal à la somme des moments des composantes de la force autour du point.
Le moment d’une force en un point est le produit de la distance perpendiculaire au point d’application et de la force appliquée.
Il peut également être déterminé en résolvant la force en ses composantes et en multipliant les composantes individuelles par le bras de moment correspondant.
Prenons l’exemple d’une vanne où un volant est monté sur un pipeline. Lorsqu’une force est appliquée pour faire tourner la roue, le moment de la force autour du centre peut être déterminé en multipliant l’intensité de la force par la distance perpendiculaire du centre au point d’application.
La force appliquée peut également être résolue en ses composantes, et le moment peut être déterminé en additionnant les produits de chaque composante de force avec sa distance correspondante.

<ol>
	<li>Hibbeler, R.C. (2016). Génie mécanique \u2012 Statique et dynamique. Hoboken, New Jersey : Pearson Prentice Hall. p. 132.</li>
</ol>

principe des moments

Le principe des moments, également appelé théorème de Varignon, est un concept fondamental en physique et en ingénierie qui décrit l'équilibre d'un corps rigide sous l'influence de forces externes. Le principe énonce que le moment d'une force par rapport à un point est égal à la somme des moments des composantes de la force par rapport au même point. Le moment est calculé en multipliant la magnitude de la force par la distance perpendiculaire entre le point d'application et le point par rapport auquel le moment est calculé. Considérez une vanne où une manivelle est fixée sur un tuyau. Lorsque quelqu'un applique une force pour faire tourner la manivelle, le moment de la force par rapport au centre peut être déterminé en multipliant la magnitude de la force par la distance perpendiculaire entre le centre et le point d'application de la force. Cependant, le calcul peut devenir plus complexe si la force appliquée n'est pas perpendiculaire à la vanne ou a plusieurs composantes. Dans ce cas, nous pouvons décomposer la force en ses vecteurs composants et calculer individuellement le moment de chaque composante en la multipliant par la distance perpendiculaire entre le point d'application de cette composante et le point par rapport auquel le moment est calculé. Une fois que chacun des moments a été calculé, nous pouvons les additionner pour déterminer le moment global de la force par rapport au point en question. Le principe des moments peut être utilisé dans un large éventail d'applications, de l'ingénierie structurelle à la conception mécanique. En calculant les moments des forces agissant sur un système ou une structure, nous pouvons déterminer s'il est en équilibre ou s'il va tourner ou se déplacer en raison d'un déséquilibre des forces.

Principe des moments

Le principe des moments, également connu sous le nom de théorème de Varignon, est un concept fondamental en physique et en ingénierie qui décrit l'équilibre d'un ...

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Principle of Moments

resolving forces in moment calculations

The principle of moments, also called Varignon's theorem, explains how a force creates rotation about a point. It is a key idea in physics and engineering. It also helps describe when a rigid body stays in equilibrium under external forces.

The moment of a force is found by multiplying the force by the perpendicular distance from the point of application to the point being studied. A larger force or a larger distance gives a larger moment. This makes the idea useful for checking how strongly a force can turn an object.

A valve with a hand wheel on a pipeline gives a clear example. When a person pushes on the wheel, the moment about the center depends on the force and the perpendicular distance from the center to where the force is applied. If the force is not perpendicular to the valve, the calculation is less direct.

In that case, the force can be split into component vectors. Each component has its own moment, and each one is found using the perpendicular distance from the point of application of that component to the point of rotation. After the moments are found, they are added together to get the overall moment about the point.

This method is used in structural engineering and mechanical design. It helps show whether a system or structure is in equilibrium. It also shows when an imbalance of forces may cause rotation or motion.

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key terms and concepts

Learn how the principle of moments breaks a force into components and uses distance to find rotation in a valve, structure, or other rigid body.

Resolving Forces in Moment Calculations | JoVE K12

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

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Resolving Forces in Moment Calculations

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