Name: free-body diagrams for force analysis
Uploaded: 2023-09-22T11:49:20.000Z
Duration: 1 min 28 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Physical Science

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

HS-PS2-3

Free-body Diagram

A representação visual de todas as forças que atuam sobre a partícula é chamada de diagrama de corpo livre ou diagrama de força. Transforma problemas complexos em representações simples.
Em um diagrama de corpo livre, a direção das setas indica a direção das forças, enquanto o comprimento das setas representa a magnitude das forças.
Considere um carrinho estacionário no qual duas caixas de papelão estão empilhadas.
Aqui, os dois sistemas de interesse, caixa um e caixa dois, podem ser considerados sistemas isolados e podem ser representados usando um diagrama de corpo livre na forma de um contorno simples ou um ponto.
As forças que atuam na caixa um são a força gravitacional, que define seu peso, e a força normal de contrapeso devido à caixa dois.
Da mesma forma, as forças na caixa dois são seu próprio peso, a força normal devida ao carrinho e o peso da caixa um.
Os diagramas de corpo livre desempenham um papel fundamental no processo de resolução de problemas como uma transição de uma situação física específica para uma equação matemática abstrata na mecânica.

<ol>
	<li>Hibbeler, R.C. (2016). Engenharia Mecânica \u2012 Estática e Dinâmica. Hoboken, Nova Jersey: Pearson Prentice Hall. pág. 88</li>
	<li>Cerveja, F.P.; Johnston, E.R.; Mazurek, D.F; Cromwell, PJ e Self, BP (2019). Mecânica vetorial para engenheiros \u2012 estática e dinâmica. Nova Iorque: McGraw-Hill. pág. 170-171</li>
</ol>

diagrama de corpo livre

Na mecânica, entender o movimento dos objetos é essencial, e uma ferramenta que ajuda a resolver esse problema é o diagrama de corpo livre. É uma representação gráfica simples, porém poderosa, que representa sucintamente todas as forças atuando em um objeto. Um diagrama de corpo livre pode representar um objeto estacionário ou em movimento e é usado na mecânica para explicar a causa do movimento de um objeto.

Um diagrama de corpo livre transforma um problema complexo em uma representação simples, facilitando a compreensão das forças essenciais atuando em um objeto, levando a uma equação matemática. Em muitos casos, a equação seria extremamente complexa de derivar sem o uso de diagramas de corpo livre. Para fazer um diagrama de corpo livre, comece selecionando o objeto ou sistema sob inspeção, isolando-o de seu entorno e desenhando-o como um ponto ou um contorno simples. Em seguida, represente todas as forças externas essenciais atuando no objeto ou sistema de interesse com setas. A direção das setas representa a direção da força, enquanto o comprimento das setas representa a magnitude da força. É importante observar que em um diagrama de corpo livre, a velocidade e a aceleração não são representadas, mas podem ser inferidas a partir das forças aplicadas no objeto.

Alguns tipos comuns de forças que podem ser representadas em um diagrama de corpo livre incluem peso, força normal, tensão, atrito e força aplicada. Peso se refere à força da gravidade atuando no objeto, geralmente representada por uma seta apontando para baixo. A força normal é a força entre dois objetos quando eles entram em contato um com o outro; essa força atua na direção oposta ao peso do objeto. Tensão geralmente é representada por uma seta apontando para longe do objeto na direção da força, e o atrito é a força que resiste ao deslizamento entre as superfícies. Por fim, força aplicada se refere à força aplicada ao objeto por um agente externo, como um empurrão ou uma puxada. Forças aplicadas são representadas por uma seta apontando na direção da força.

Considere um carrinho estacionário, no qual duas caixas de papelão estão empilhadas. Os dois sistemas de interesse, caixa um e caixa dois, podem ser considerados sistemas isolados e podem ser representados usando um diagrama de corpo livre. As forças atuando na caixa um são a força gravitacional, que define seu peso, e a força normal de balanceamento devida à caixa dois. Da mesma forma, as forças na caixa dois são seu peso, a força normal devido ao carrinho e o peso da caixa um.

Diagrama de Corpo Livre

Na mecânica, entender o movimento dos objetos é essencial, e uma ferramenta que ajuda a resolver esse problema é o diagrama de corpo livre. É um simples, mas ...

Education

JoVE Core

Mechanical Engineering

Engenharia Mecânica

Unit 1

Unidade 1

Equilibrium of a Particle

Equilíbrio de uma Partícula

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

free-body diagrams for force analysis

Free-body diagrams help analyze the forces acting on an object in mechanics. They give a simple picture of a stationary or moving object and show why it moves the way it does. By turning a complex situation into a clear sketch, they make it easier to write the equation needed to solve the problem.

To draw a free-body diagram, first choose the object or system you want to study. Then isolate it from its surroundings and draw it as a dot or a simple outline. Add arrows for every important external force. The direction of each arrow shows the direction of the force, and the length shows its size.

A free-body diagram does not show velocity or acceleration. Those quantities are not drawn on the diagram, but they can be inferred from the forces acting on the object. Common forces include weight, normal force, tension, friction, and applied force. Weight is the force of gravity and is usually shown with an arrow pointing downward.

Normal force is the contact force between two objects touching each other. It acts in the direction opposite to the object's weight in many situations. Tension is usually drawn as an arrow away from the object and along the direction of the pull. Friction resists sliding between surfaces. Applied force is an outside push or pull, and it is shown with an arrow in the direction of that force.

A stationary trolley with two cardboard boxes stacked on it gives a clear example. Box one and box two can each be treated as separate isolated systems and shown with their own free-body diagrams. For box one, the forces are gravitational force and the balancing normal force from box two. For box two, the forces are its weight, the normal force from the trolley, and the weight of box one.

Free-Body Diagrams for Force Analysis

equilibrium conditions for a particle

Balanced Forces and Torque in Equilibrium

Equilibrium depends on balanced forces and balanced torque. An object in equilibrium is either at rest or moving with a constant velocity. These two cases are called static equilibrium and dynamic equilibrium. Static equilibrium means the object is not moving. Dynamic equilibrium means the object is moving, but its velocity stays constant. In both cases, the forces acting on the object must balance each other. Different forces can add, subtract, or cancel each other out. When the vector sum...

free-body diagram

Free-body diagrams help analyze the forces acting on an object in mechanics. They give a simple picture of a stationary or moving object and show why it moves the way it does. By turning a complex situation into a clear sketch, they make it easier to write the equation needed to solve the problem. To draw a free-body diagram, first choose the object or system you want to study. Then isolate it from its surroundings and draw it as a dot or a simple outline. Add arrows for every important...

steps for free-body diagram

Free-Body Diagram for Two-Block Motion

A free-body diagram helps analyze two-block motion in mechanics. It shows the forces acting on a system so the net force can be found and the acceleration can be calculated. The example in this lesson uses two blocks linked by a massless string over a frictionless pulley. Block 1 moves across a table while block 2 falls under gravity. The two blocks are treated as one isolated system. External forces are then identified and drawn as vector arrows on the diagram. For block 1, the forces...

free-body diagrams: problem solving

Free-Body Diagrams on Inclined Planes

Free-body diagrams help show the forces acting on an object on an inclined plane. A free-body diagram is a simple drawing that focuses only on the object or system being studied. It leaves out extra details so the force problem is easier to analyze and solve. For an example, a 10 kg block is released on a ramp that is 30° to the horizontal. The coefficient of friction is 0.2. The diagram for this block includes the weight from gravity, the normal force, and the frictional force. These are the...

coplanar forces

Resolving Coplanar Force Components

Coplanar forces act on an object in the same plane. To analyze this kind of system, each force is resolved into x and y components using Cartesian vector form and vector algebra. This makes it possible to test whether the object is in equilibrium. A coplanar system is in equilibrium when the resultant force is zero. That means the sum of the forces in each direction must also be zero. If the forces do not balance, the object is not in equilibrium and will accelerate in the direction of the net...

categories of equilibrium

Types of Equilibrium in Forces

Equilibrium in physics describes how forces act on a body so it stays still or moves at a constant speed. In two-dimensional force systems, equilibrium can be grouped into several categories based on how the forces are arranged. Collinear equilibrium is the simplest case. The forces act along one straight line, so only one force equation is needed in the direction of those forces. The other equations are already satisfied. Coplanar concurrent equilibrium is another category. In this case, all...

key terms and concepts

Learn how free-body diagrams show weight, normal force, tension, friction, and applied force. See how isolating an object simplifies force analysis in mechanics.

Free-Body Diagrams for Force Analysis | 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.

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HS-PS2-2

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HS-PS2-6

Free-Body Diagrams for Force Analysis

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