Name: centroid of a quarter circle wire
Uploaded: 2025-05-22T09:06:05.000Z
Duration: 1 min 3 s
Channel: JoVE

円弧の形に曲げられた細いワイヤーを考えてみましょう。極座標は、この 4 分の 1 の円形ワイヤ セグメントの重心を効果的に計算するために使用されます。
円弧の重心は、ワイヤを小さな微分要素に分割し、各要素の長さが半径と微分角度に等しいことで計算できます。
要素の重心の x 座標と y 座標は、x 軸に対して要素が行う半径と角度で表すことができます。
次に、円弧の重心は、これらすべての要素の加重平均を計算することによって計算されます。
ワイヤが 1/4 円を従属させると、式は 0 の限界から 2 を超える π まで積分できます。この結果から、1/4 の円形ワイヤ セグメントの重心座標が得られます。
重心の x 座標と y 座標は、問題の円対称性により数値的に等しくなります。

<ol>
	<li>ヒベラー、RC(2016)。エンジニアリングメカニクス:静力学。第14版、ニュージャージー州:ピアソン。472ページ。</li>
</ol>

物体の重心：問題解決

Centroid of a Body: Problem Solving

物体の重心は、エンジニアリングや物理学において重要な概念です。物体の重心を見つけることで、その安定性やバランスポイント、さらには設計を決定することができます。この文脈では、四半円の形状に折れ曲がった細いワイヤーを考えてみましょう。重心を計算するためには、極座標が使用されます。ワイヤーはまず、半径を微小な角度で乗じた長さと等しい微小な差分要素に分割されます。

各要素の重心の x 座標と y 座標は、要素の x 軸に対する角度や半径に関して表されます。円弧の重心は、それらの要素の重み付き平均を計算することによって得られます。ここで、各要素の重みはその長さに比例します。

ワイヤーが四半円であるため、微小要素はゼロからπ/2まで積分することができます。結果として、四半円ワイヤーセグメントの重心座標が得られます。この場合、重心の x 座標と y 座標は、問題の円形対称性のため数値的に等しいです。

この方法は、曲線アーチトラスの重心を決定するためにも適用することができます。計算された重心は、アーチが崩れることなく運べる最大の荷重や、アーチ上の特定のポイントに作用する力を決定するために使用することができます。物体の重心を知ることは、機械工学において多くの利点を提供し、構造物の設計と安定性において重要です。

物体の重心は、工学と物理学において重要な概念です。体の重心を見つけることは、その安定性、バランスを判断するのに役立ちます...

Education

JoVE Core

Mechanical Engineering

機械工学

Unit 1

ユニット1

Center of Gravity and Centroid

重心と図心

KEY TERMS AND CONCEPTS

主要用語と概念

centroid of a quarter circle wire

The centroid of a quarter circle wire shows how balance points can be found for curved shapes. In physics and engineering, the centroid helps describe stability, balance, and design. For a thin wire bent into a quarter circular arc, the goal is to find the centroid coordinates of the arc itself.

Polar coordinates are used to solve this centroid problem. The wire is divided into small differential elements, and each element has a length equal to the radius times the differential angle. The x- and y-coordinates of each element’s centroid are written in terms of the radius and the angle measured from the x-axis.

The centroid of the whole arc is found by taking a weighted average of all these small elements. The weight of each piece depends on its length. Because the shape is a quarter circle, the integration runs from 0 to π/2.

This calculation gives the centroid coordinates for the quarter circle wire segment. In this case, the x- and y-coordinates are numerically equal because of the symmetry of the circular arc. The same method can also be used for curved arch trusses.

Knowing the centroid of an arch can help engineers estimate the maximum load it can carry without collapsing. It can also help determine the forces acting at specific points on the arch. Centroid calculations are therefore important in the design and stability of structures.

Centroid of a Quarter Circle Wire

center of gravity

Center of Gravity in Balance and Design

The center of gravity is the point where an object’s weight appears to act. It is the spot used to balance the object most evenly. In mechanics, this point helps explain stability and moments of inertia. The center of gravity does not always sit inside the object’s shape. In some cases, it can lie outside the body. That is why the idea is useful for both simple and more complex shapes. Its location can be found with the principle of moments. The object is divided into very small parts, and...

center of mass

Center of Mass in Motion

The center of mass helps explain how an object moves through space. It is the point where the total mass of an object can be treated as concentrated. This idea applies to objects of different shapes and sizes. The center of mass is related to the center of gravity, but they are not the same. The center of gravity is the point where an object’s weight seems to be concentrated. It can be used to balance an object perfectly. Knowing the center of mass also helps predict motion. When a ball is...

centroid of a body

Finding the Center of a Body

The centroid is the geometric center of a body. It is an important idea in engineering, physics, and mechanics. For many objects, it lies inside the body. A body with holes or cavities can be an exception. For a homogeneous body, the centroid matches the center of mass or the center of gravity. Homogeneous means the material has a uniform density. In that case, the centroid can often be found by balancing the moments of the body’s volume. Symmetry can also help locate the centroid. If a...

centroid of a body: problem solving

The centroid of a quarter circle wire shows how balance points can be found for curved shapes. In physics and engineering, the centroid helps describe stability, balance, and design. For a thin wire bent into a quarter circular arc, the goal is to find the centroid coordinates of the arc itself. Polar coordinates are used to solve this centroid problem. The wire is divided into small differential elements, and each element has a length equal to the radius times the differential angle. The x-...

centroid for the paraboloid of revolution

centroid-for-the-paraboloid-of-revolution

Centroid and Uses of a Paraboloid Shape

The centroid of a paraboloid of revolution is the point where its mass is balanced. A paraboloid of revolution is an axially symmetric surface made by rotating a parabola around its axis. In engineering, this location matters because it helps show how forces spread across the shape. Knowing the centroid can help when building parts that must handle stress and pressure reliably. The paraboloid shape has useful structural properties, including rotational symmetry and strength against stress...

composite bodies

Center of Gravity in Composite Bodies

Composite bodies are made of multiple connected parts that act as one larger object. Each part still has its own weight and center of gravity. To find the center of gravity of the whole body, engineers must account for every part. When the density or specific weight is constant, the center of gravity matches the centroid. The centroid is the geometric center of a shape. This idea is useful when analyzing parts that behave as a single unit. Composite bodies are common in mechanical engineering.

theorems of pappus and guldinus

Surface Area and Volume by Centroid Paths

Pappus and Guldinus theorems help find the surface area and volume of bodies of revolution. A body of revolution is formed when a plane curve or plane area is turned around an axis that does not intersect it. For surface area, a curve is revolved around a non-intersecting axis. A small line element on the curve creates a thin ring as it moves. Adding these ring areas gives the total surface area of the solid. The first theorem says that this surface area equals the length of the generating...

theorems of pappus and guldinus: problem solving

theorems-of-pappus-and-guldinus-problem-solving

Pappus and Guldinus Theorems for Surface Area

Pappus and Guldinus's theorems help find the surface area and volume of composite shapes. These rules are useful when a solid is made from simple parts that are hard to measure directly. A cylindrical storage tank with a conical top is one example. The tank can be split into two simple shapes: a cylinder and a cone. To find surface area, the first theorem is used for the solid formed by revolving each generating curve around a non-intersecting axis. The calculation uses the length of the...

resultant of a general distributed loading

resultant-of-a-general-distributed-loading

Finding the Resultant of Distributed Loads

Distributed loads create a force that is spread over a surface instead of acting at one point. To analyze this kind of loading, engineers use a single resultant force. That force represents the net effect of the entire load. This idea is important in structures that face non-uniform loads. Wind can push on buildings and towers with changing speed and direction, so the load is not evenly spread. Bridges also experience non-uniform loading from vehicles, and some parts of the bridge can feel...

fluid pressure

How Depth Changes Fluid Pressure

Fluid pressure changes with depth in liquids used in engineering systems. It matters in hydraulic systems, pumps, and valves, where the forces from moving and resting fluid must be considered to prevent damage or failure. For a fluid at rest, Pascal’s law says the pressure is equal in all directions. Pressure is force per unit area. Its size depends on the fluid’s specific weight, or mass density, and on how deep the measurement point is below the fluid surface. This relationship can be...

fluid pressure over flat plate of constant width

fluid-pressure-over-flat-plate-of-constant-width

Center of Pressure on a Submerged Plate

Fluid pressure on a submerged flat plate depends on depth and shape. A plate under water experiences pressure acting normal to its surface, and the force is spread across the whole area. For a rectangular plate of constant width, this pressure increases from the top edge to the bottom edge. Because the pressure rises with depth, the loading forms a trapezoidal distribution. The resultant force on the plate comes from the trapezoidal volume of water with a specific weight. The line of action of...

fluid pressure over curved plate of constant width

fluid-pressure-over-curved-plate-of-constant-width

Finding Force on a Curved Plate in Water

Fluid pressure on a curved plate of constant width changes in both size and direction. That makes the total force hard to find directly. A common method is to split the force into horizontal and vertical parts and then combine them. The calculation becomes simpler by replacing the distributed load with an equivalent two-dimensional loading. The first step is to include the weight of the liquid inside the block. That force equals the specific weight of the liquid times the plate thickness and...

fluid pressure over flat plate of variable width

fluid-pressure-over-flat-plate-of-variable-width

A submerged flat plate experiences fluid pressure that changes with depth. This pressure can create effects such as drag and buoyancy. To study a flat plate with variable width, the pressure distribution across the plate must be analyzed first. The force on a small strip of the plate is found by multiplying the pressure by the strip’s differential area. The pressure can also be written using the fluid’s specific weight and the depth of that strip below the surface. To find the total, or...

key terms and concepts

Learn how to find the centroid of a quarter circle wire using polar coordinates, integration, and symmetry, with applications to curved arches and structural stability.

Centroid of a Quarter Circle Wire | JoVE K12

JoVE Core 機械工学は、平衡、力、トラス解析、構造力学などの重要なトピックをカバーする簡潔でわかりやすいアニメーション ビデオを提供します。実際のアプリケーションを探索し、科学者主導の実験を通じてこれらのコンセプトが実際に動作しているのを目撃してください。

mechanical engineering

Centroid of a Quarter Circle Wire

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