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

도르래 위에 질량이 없는 끈으로 연결된 두 블록의 시스템을 생각해 보십시오. 블록 1은 중력에 의해 떨어지면서 블록 2에 의해 당겨진 테이블 위로 미끄러지고 있습니다. 
시스템의 가속도는 시스템에 가해지는 알짜 힘을 계산하여 파생될 수 있습니다.
이 시스템에 대한 자유물체 다이어그램은 두 블록을 윤곽선으로 표시하여 그릴 수 있습니다. 여기서 블록은 격리된 것으로 간주됩니다.
그들에 작용하는 외부 힘은 식별되고 벡터 화살표로 표시됩니다.
블록 1의 힘은 무게, 수직력, 로프로 인한 인장력, 움직임을 일으키는 장력에 반대하는 마찰력입니다.
유사하게, 블록 2에 작용하는 힘은 무게와 인장력입니다.
뉴턴의 운동 제2법칙을 블록에 적용하면 알짜 힘에 대한 방정식을 도출할 수 있습니다.
대수 연산을 사용하고 항을 재배열하면 시스템 가속도의 크기를 얻을 수 있습니다.

<ol>
	<li>히벨러, R.C. (2016). Engineering Mechanics \u2012 정역학 및 동역학. 뉴저지 호보켄: 피어슨 프렌티스 홀. 89쪽</li>
	<li>맥주, F.P.; 존스턴, ER; 마주렉, D.F; 크롬웰, PJ 및 셀프, BP (2019). 엔지니어를 위한 벡터 역학 \u2012 Statics and Dynamics. 뉴욕 : McGraw-Hill. 쪽 171-172</li>
</ol>

자유물체도를 위한 단계

역학에서 물체의 동작을 연구할 때 사용할 수 있는 가장 중요한 도구 중 하나는 자유 물체도입니다. 마찰이 없는 도르래 위에 질량이 없는 끈으로 연결된 두 블록으로 이루어진 시스템의 간단한 예를 생각해 보세요. 블록 2가 중력에 의해 떨어지면서 블록 1은 블록 2에 의해 당겨진 테이블 위로 미끄러지고 있습니다.
시스템의 가속도를 구하기 위해서는 시스템에 작용하는 알짜힘을 계산하는 것이 먼저 필요합니다. 이를 위해서는 환경으로부터 고립된 단일 시스템으로 간주되는 두 블록을 나타내기 위한 자유물체도를 만들 수 있습니다. 그런 다음 외부 힘이 도표에서 식별되고 벡터 화살표로 표시됩니다.
블록 1을 볼 때 여러 힘이 블록 1에 작용하고 있습니다. 여기에는 무게, 수직력, 밧줄에 의한 장력, 그리고 장력에 대항하는 마찰력이 포함되어 있으므로 운동을 일으킵니다. 블록 2의 경우 무게와 장력만이 블록 2에 작용하는 유일한 힘입니다.
자유물체도가 만들어지면, 뉴턴의 운동 제2법칙을 블록에 적용할 수 있습니다. 이렇게 하면 시스템에 작용하는 알짜힘에 대한 식을 유도할 수 있습니다. 이 식은 블록의 질량, 시스템의 가속도, 각 블록에 작용하는 힘을 포함합니다. 
방정식이 있으면 대수 연산을 사용하여 항을 재정렬하고 계의 가속도 크기를 해결할 수 있습니다. 그 결과는 주어진 힘에서 시스템이 어떻게 행동하는지를 나타내는 수치가 될 것입니다.
이 상황에서 자유물체도의 중요성은 아무리 강조해도 지나치지 않습니다. 그것은 작용하는 힘을 명확하고 간결하게 시스템의 가속도를 더 쉽고 정확하게 계산할 수 있습니다. 이 도구가 없다면 블록의 동작과 블록에 작용하는 힘을 이해하고 분석하는 것이 훨씬 더 어려울 것입니다.

역학에서 물체의 동작을 연구할 때 사용할 수 있는 가장 중요한 도구 중 하나는 자유물체 다이어그램입니다. 간단한 것을 고려하십시오 ...

Education

교육

JoVE Core

Mechanical Engineering

기계공학

Unit 1

제1단원

Equilibrium of a Particle

입자의 평형

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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

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 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

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HS-PS2-6

Free-Body Diagram for Two-Block Motion

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