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

As forças internas são geradas dentro de um corpo devido à interação entre suas partículas. Essas forças incluem tensão, compressão e cisalhamento. 
As forças internas existem em pares colineares de igual magnitude, mas em direções opostas. Eles se cancelam entre todas as partes conectadas, resultando no equilíbrio do corpo.
O peso de um corpo é uma força externa representada por uma única força resultante agindo através do centro de gravidade do corpo.
É o ponto em que um corpo se equilibra, desde que nenhuma força externa atue sobre ele.
Um corpo simétrico ou uniforme tem seu centro de gravidade em seu centro geométrico. No entanto, para um corpo irregular ou não uniforme, ele está descentralizado em direção ao lado mais pesado.
Considere uma viga presa a um guindaste no centro, com cargas conectadas em suas extremidades. Se a carga de um lado se tornar pesada, o centro de gravidade se afastará da linha central da viga, potencialmente causando tombamento.
O centro de gravidade deve ser identificado para garantir a estabilidade e o gancho de elevação deve ser colocado diretamente acima dele.

<ol>
	<li>Russell C. Hibbeler. (2016). Engenharia Mecânica: Estática e Dinâmica. Pearson. Pág. 212.</li>
</ol>

forças internas e centro de gravidade

Internal Forces and Center of Gravity

As forças internas e o centro de gravidade são conceitos fundamentais na mecânica, desempenhando um papel crucial na compreensão do comportamento e estabilidade de estruturas e objetos em diversas condições. Uma compreensão abrangente desses princípios é essencial para engenheiros, arquitetos e designers criarem sistemas seguros e eficientes.

As forças internas são geradas dentro de um corpo devido à interação entre suas partículas. Essas forças podem ser categorizadas em tensão, compressão e forças de cisalhamento. Essas forças internas existem em pares colineares com a mesma magnitude, mas direções opostas. Elas se cancelam entre todas as partes conectadas, mantendo o equilíbrio do corpo.

O peso de um corpo é uma força externa representada por uma única força resultante que age pelo centro de gravidade do corpo. O centro de gravidade é o ponto em que um corpo se equilibra quando nenhuma força externa está agindo sobre ele. O centro de gravidade está localizado no centro geométrico para corpos simétricos ou uniformes. No entanto, o centro de gravidade pode estar deslocado em direção ao lado mais pesado para corpos irregulares ou não uniformes.

Compreender as forças internas e o centro de gravidade é crucial para analisar e manter a estabilidade e o equilíbrio de várias estruturas e objetos. Por exemplo, na engenharia civil, esses princípios são usados para projetar pontes, prédios e outras infraestruturas capazes de suportar forças externas, como vento, terremotos e cargas de tráfego.

Na engenharia mecânica, o conhecimento das forças internas e do centro de gravidade é aplicado para projetar máquinas, veículos e outros sistemas mecânicos que possam operar de forma segura e eficiente sob diferentes cargas e condições.

Na engenharia aeroespacial, determinar com precisão o centro de gravidade de aeronaves e espaçonaves é vital para garantir estabilidade e controle durante o voo. Uma mudança no centro de gravidade pode ter consequências graves para o desempenho e a segurança desses veículos.

Forças internas e Centro de Gravidade

As forças internas e o centro de gravidade são conceitos fundamentais na mecânica, desempenhando um papel crucial na compreensão do comportamento e estabilidade de ...

Education

JoVE Core

Mechanical Engineering

Engenharia Mecânica

Unit 1

Unidade 1

Equilibrium of a Rigid Body

Equilíbrio de um Corpo Rígido

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

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

O JoVE Core Mechanical Engineering oferece vídeos animados concisos e de fácil compreensão que abrangem tópicos-chave como equilíbrio, forças, análise de treliças e mecânica estrutural. Explore suas aplicações no mundo real e observe esses conceitos em ação por meio de experimentos conduzidos por cientistas.

mechanical engineering

Forces Inside a Body and Balance

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