Name: forces inside a body and balance
Uploaded: 2023-09-22T11:49:22.000Z
Duration: 1 min 25 s
Channel: JoVE

내부 힘은 입자 간의 상호 작용으로 인해 신체 내에서 생성됩니다. 이러한 힘에는 인장, 압축 및 전단력이 포함됩니다. 
내부 힘은 같은 크기의 동일 선상 쌍으로 존재하지만 방향은 반대입니다. 그것들은 연결된 모든 부분 사이에서 상쇄되어 신체의 평형을 초래합니다.
물체의 무게는 물체의 무게 중심을 통해 작용하는 단일 결과 힘으로 표시되는 외부 힘입니다.
그것은 신체가 외부의 힘이 작용하지 않는 한 스스로 균형을 잡는 지점입니다.
대칭 또는 균일한 물체는 기하학적 중심에 무게 중심이 있습니다. 그러나 불규칙하거나 균일하지 않은 몸체의 경우 더 무거운 쪽으로 중심에서 벗어납니다.
중앙의 크레인에 부착된 빔과 그 끝에 하중이 연결되어 있다고 생각해 보십시오. 한쪽 면의 하중이 무거워지면 무게 중심이 빔의 중심선에서 멀어지므로 잠재적으로 기울어질 수 있습니다.
안정성을 보장하기 위해 무게 중심을 식별해야 하며 리프팅 후크는 그 바로 위에 배치해야 합니다.

<ol>
	<li>러셀 C. 히벨러. (2016). 엔지니어링 역학 : 정적 및 역학. 피어슨. 212쪽.</li>
</ol>

내력과 무게중심

Internal Forces and Center of Gravity

내력과 무게 중심은 역학의 기본 개념으로 다양한 조건에서 구조물과 물체의 거동과 안정성을 이해하는 데 중요한 역할을 합니다. 이러한 원리에 대한 포괄적인 이해는 기술자, 건축가, 설계자가 안전하고 효율적인 시스템을 만드는 데 필수적입니다.
내력은 입자들 사이의 상호작용으로 인해 물체 내부에 발생합니다. 이 힘들은 장력, 압축력, 전단력으로 분류할 수 있습니다. 이 내부 힘들은 크기는 같지만 방향은 반대인 동일한 선형 쌍으로 존재합니다. 이들은 연결된 모든 부분 사이에서 서로 상쇄되어 신체의 평형을 유지합니다.
물체의 무게는 물체의 무게중심을 통해 작용하는 하나의 결과적인 힘으로 표현되는 외력입니다. 외력이 작용하지 않을 때 물체가 균형을 잡는 지점을 무게중심이라고 합니다. 대칭적이거나 균일한 물체의 경우 무게중심이 기하학적 중심에 위치합니다. 그러나 불규칙하거나 균일하지 않은 물체의 경우 무게중심이 무거운 쪽으로 어긋날 수 있습니다.
내부 힘과 무게 중심을 이해하는 것은 다양한 구조물과 물체의 안정성과 평형을 분석하고 유지하는 데 매우 중요합니다. 예를 들어, 토목공학에서 이러한 원리는 바람, 지진, 교통 부하와 같은 외부 힘을 견딜 수 있는 다리, 건물 및 기타 기반 시설을 설계하는 데 사용됩니다.
기계공학에서 내력과 무게중심에 대한 지식은 다양한 하중과 조건에서 안전하고 효율적으로 작동할 수 있는 기계, 차량 및 기타 기계 시스템을 설계하는 데 적용됩니다.
항공우주공학에서 항공기와 우주선의 무게 중심을 정확하게 결정하는 것은 비행 중 안정성과 제어를 보장하는 데 매우 중요합니다. 무게 중심의 이동은 이러한 차량의 성능과 안전에 심각한 결과를 초래할 수 있습니다.

내부 힘과 무게 중심은 역학의 기본 개념으로, 역학의 거동과 안정성을 이해하는 데 중요한 역할을 합니다.

Education

교육

JoVE Core

Mechanical Engineering

기계공학

Unit 1

제1단원

Equilibrium of a Rigid Body

강체의 평형

KEY TERMS AND CONCEPTS

주요 용어 및 개념

forces inside a body and balance

Internal forces and the center of gravity help explain how objects stay in balance. These mechanics ideas matter for structures, machines, and vehicles that must remain stable under different loads and conditions.

Internal forces are created inside a body when its particles interact. They can appear as tension, compression, or shear forces. These forces act in collinear pairs with equal magnitude and opposite direction. Between connected parts, they cancel each other and help keep the body in equilibrium.

A body’s weight is an external force. It is shown as one resultant force acting through the center of gravity. The center of gravity is the point where a body balances when no external force acts on it. For symmetrical or uniform bodies, this point is at the geometric center. For irregular or non-uniform bodies, it may shift toward the heavier side.

These ideas are important in civil engineering, mechanical engineering, and aerospace engineering. Engineers use them to design bridges, buildings, machines, vehicles, aircraft, and spacecraft that can handle wind, earthquakes, traffic loads, and other forces. If the center of gravity changes, the stability and safety of an aircraft or spacecraft can be affected.

Forces Inside a Body and Balance

conditions of equilibrium

Rigid Body Force Balance in Equilibrium

Rigid body equilibrium depends on a balance of external forces and moments. A rigid body is in equilibrium when it has no translational motion and no rotational motion. This happens when the net force and the net couple acting on the body are both zero. Internal forces are not used when checking equilibrium. These forces act in equal and opposite pairs inside the body, so they cancel each other. Because of that, they do not affect the overall motion or change in motion of the rigid body. The...

support reactions

Types of Structural Supports

Types of structural supports control how a coplanar force system moves and reacts under load. A coplanar force system is a set of forces that all lie in the same plane. The supports create reactions at the point of contact. These reactions help keep a structure stable under external forces. Supports work by stopping translation with an equal and opposite force. They can also stop rotation by applying a couple moment in the opposite direction. In structural design, these reactions are important...

internal forces and center of gravity

Internal forces and the center of gravity help explain how objects stay in balance. These mechanics ideas matter for structures, machines, and vehicles that must remain stable under different loads and conditions. Internal forces are created inside a body when its particles interact. They can appear as tension, compression, or shear forces. These forces act in collinear pairs with equal magnitude and opposite direction. Between connected parts, they cancel each other and help keep the body in...

alternative sets of equilibrium equations

alternative-sets-of-equilibrium-equations

Equilibrium Conditions for a Supported Plate

Equilibrium conditions for a supported plate are used to describe when forces and moments balance. In this state, the plate has no net movement and no rotation. Engineers use these equations to study how structures behave under external loads. In many cases, the standard equilibrium equations are enough. But some systems need an alternative set of equations to match the geometry of the support points. A rectangular plate supported at points A, B, and C is one example. For this plate, the...

two force member

Two-Force Body Equilibrium

A two-force body is a rigid body acted on by only two external forces. In equilibrium, those two forces must have the same magnitude, the same line of action, and opposite directions. This balance is what keeps the body at rest. For a plate with forces F1 and F2 applied at points A and B, equilibrium means the sum of moments about any axis is zero. If moments are summed about point A, the moment from F2 must be zero. That means the line of action of F2 must pass through point A. The same idea...

three force member

Solving a Three-Force Member Example

A three-force member is a rigid body acted on by three forces at three points. The forces must have concurrent lines of action. If the forces are parallel, their lines of action stay parallel instead. A dumpster provides the example used here. It is connected to a pin support at point A and to a pin on a hydraulic cylinder at point B. The hydraulic cylinder acts as a two-force member in equilibrium. The dumpster weight acts through the center of gravity, and the support reaction acts at point...

equations of equilibrium in three dimensions

equations-of-equilibrium-in-three-dimensions

Checking Force Balance in 3D Structures

Checking force balance in 3D structures is a key step when a system is at rest. The vector and scalar equations of equilibrium are used to test whether a body is stable and will not collapse or fall apart. These equations give a clear way to study the forces acting on a body. The vector equations of equilibrium require the vector sum of all external forces on a body to equal zero. They also require the vector sum of the couple moments and the moments of all forces about a point to equal zero.

support reactions in three dimensions

3D Support Types for Stability and Motion

Support reactions in three dimensions keep structures stable and in equilibrium. They stop unwanted translation and rotation, so a design can handle external forces safely and work as intended. These reactions are important in many structures and systems. A ball and socket joint is one support that allows free rotation about any axis. It does not provide a moment that resists turning. At the same time, it restricts motion in space with three reaction forces along the three dimensions. A...

constraints and statical determinacy

Constraints in Structural Equilibrium

Constraints in structural engineering control how a body can move and help keep it in mechanical equilibrium. A constraint is a restriction on motion. When the right number of constraints is used, the system can stay balanced with the fewest supports needed. A system with the proper number of supports is called statically determinate. In that case, the unknown reaction forces can be found from equations of equilibrium. These systems are the easiest to analyze and design because the forces can...

key terms and concepts

Learn how internal forces and the center of gravity affect balance, stability, and equilibrium in structures, machines, and vehicles.

Forces Inside a Body and Balance | 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.

mechanical engineering

Forces Inside a Body and Balance

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