Name: free-body diagram for two-block motion
Uploaded: 2025-05-22T09:06:02.000Z
Duration: 1 min 22 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

Steps for Free-Body Diagram

Considere um sistema de dois blocos acoplados por uma corda sem massa sobre uma polia. O bloco 1 está deslizando sobre uma mesa puxada pelo bloco 2 à medida que cai sob a gravidade. 
A aceleração do sistema pode ser derivada calculando a força resultante no sistema.
Um diagrama de corpo livre para este sistema pode ser desenhado representando os dois blocos com seu contorno. Aqui, os blocos são considerados isolados.
As forças externas que atuam sobre eles são identificadas e representadas por setas vetoriais.
As forças no bloco 1 são seu peso, força normal, força de tensão devido à corda e força de atrito oposta à força de tensão que causa o movimento.
Da mesma forma, as forças que atuam no bloco 2 são seu peso e a força de tração.
Aplicando a segunda lei do movimento de Newton aos blocos, uma equação para a força resultante pode ser derivada.
Usando a operação algébrica e reorganizando os termos, a magnitude da aceleração do sistema pode ser obtida.

<ol>
	<li>Hibbeler, R.C. (2016). Engenharia Mecânica \u2012 Estática e Dinâmica. Hoboken, Nova Jersey: Pearson Prentice Hall. pág. 89</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. 171-172</li>
</ol>

passos para o diagrama de corpo livre

Quando se trata de estudar o comportamento de objetos na mecânica, uma das ferramentas mais importantes disponíveis é o diagrama de corpo livre. Considere um exemplo simples de um sistema de dois blocos acoplados por uma corda sem massa sobre uma roldana sem atrito. O Bloco 1 está deslizando sobre uma mesa puxado pelo Bloco 2 enquanto o Bloco 2 cai sob a gravidade.

Para encontrar a aceleração do sistema, é necessário primeiro calcular a força líquida no sistema. Para isso, um diagrama de corpo livre pode ser criado para representar os dois blocos, que são considerados como um único sistema isolado do ambiente. As forças externas são então identificadas e representadas por setas vetoriais no diagrama.

Ao olhar para o Bloco 1, várias forças atuam sobre ele. Isso inclui seu peso, a força normal, a força de tensão devida à corda e a força de fricção que se opõe à força de tensão, causando assim o movimento. Para o Bloco 2, seu peso e as forças de tensão são as únicas forças atuando nele.

Uma vez que o diagrama de corpo livre tenha sido criado, é possível aplicar a segunda lei de Newton do movimento aos blocos. Ao fazer isso, uma equação para a força líquida atuando no sistema pode ser derivada. Essa equação incluirá as massas dos blocos, a aceleração do sistema e as forças atuando em cada bloco.

Com a equação em mãos, é então possível usar operações algébricas para rearranjar os termos e resolver a magnitude da aceleração do sistema. O resultado será um valor numérico que representa como o sistema se comportará sob as forças dadas.

A importância de um diagrama de corpo livre nessa situação não pode ser exagerada. Ele fornece uma representação clara e concisa das forças em jogo, permitindo assim um cálculo mais fácil e preciso da aceleração do sistema. Sem essa ferramenta, seria muito mais difícil entender e analisar o comportamento dos blocos e as forças atuando sobre eles.

Passos para o Diagrama de Corpo Livre

Quando se trata de estudar o comportamento de objetos em mecânica, uma das ferramentas mais importantes disponíveis é o diagrama de corpo livre. Considere um simples ...

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 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 include weight, the normal force, tension from the rope, and friction that opposes the tension force. For block 2, the forces are its weight and the tension force.

After the free-body diagram is complete, Newton’s second law of motion can be applied to the blocks. This gives an equation for the net force on the system. The equation includes the masses of the blocks, the acceleration of the system, and the forces acting on each block.

With the equation set up, algebra can be used to rearrange the terms and solve for the magnitude of the acceleration. The result is a numerical value that describes how the system will move under the given forces. The diagram makes the force analysis clearer and more accurate.

Free-Body Diagram for Two-Block Motion

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 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...

steps for free-body diagram

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

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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...

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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 a free-body diagram is used to analyze two blocks connected by a string and pulley, identify forces, and solve for acceleration.

Free-Body Diagram for Two-Block Motion | 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-PS2-6

Free-Body Diagram for Two-Block Motion

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