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

ضع في اعتبارك نظاما من كتلتين مقترنة بخيط عديم الكتلة فوق بكرة. تنزلق الكتلة 1 فوق طاولة تجرها الكتلة 2 لأنها تقع تحت الجاذبية. 
يمكن اشتقاق تسارع النظام عن طريق حساب القوة الصافية على النظام.
يمكن رسم مخطط الجسم الحر لهذا النظام من خلال تمثيل الكتلتين بمخططهما. هنا ، تعتبر الكتل معزولة.
يتم تحديد القوى الخارجية المؤثرة عليها وتمثيلها بأسهم متجهة.
القوى الموجودة على الكتلة 1 هي وزنها ، وقوتها الطبيعية ، وقوة الشد الناتجة عن الحبل ، وقوة الاحتكاك التي تعارض قوة التوتر المسببة للحركة.
وبالمثل ، فإن القوى المؤثرة على الكتلة 2 هي وزنها وقوة التوتر.
بتطبيق قانون نيوتن الثاني للحركة على الكتل ، يمكن اشتقاق معادلة القوة المحصلة.
باستخدام العملية الجبرية وإعادة ترتيب المصطلحات ، يمكن الحصول على حجم تسارع النظام.

<ol>
	<li>هيبلر ، آر سي (2016). الميكانيكا الهندسية - الإحصاء والديناميكيات. هوبوكين ، نيو جيرسي: قاعة بيرسون برنتيس. ص 89</li>
	<li>بير ، إف بي ؛ جونستون ، إي آر ؛ مازوريك ، د. إف. كرومويل ، بي جيه وسيلف ، ب. (2019). ميكانيكا المتجهات للمهندسين - الإحصاء والديناميكيات. نيويورك: ماكجرو هيل. ص 171-172</li>
</ol>

خطوات تتعلق بمخطط الجسم الحر.

<div style="direction:rtl">عند دراسة سلوك الأجسام في الميكانيكا، يُعتبر مخطط الجسم الحر أحد أهم الأدوات المتاحة. لنأخذ مثالًا بسيطًا لنظام يتكون من مجسمين متصلتين بواسطة خيط له كتلة مهملة يمر فوق بكرة لا تتسبب في احتكاك. المجسم الأول ينزلق فوق طاولة بينما يسحبه المجسم الثاني الذي يسقط تحت تأثير الجاذبية. لإيجاد تسارع حركة النظام، يجب أولًا حساب القوة المحصلة المؤثرة عليه. لتحقيق ذلك، يمكن إنشاء مخطط الجسم الحر لتمثيل المجسمين كنظام واحد معزول عن البيئة المحيطة. بعد ذلك، يتم تحديد القوى الخارجية المؤثرة وتمثيلها بأسهم متجهات على المخطط. عند النظر إلى المجسم1، يمكن ملاحظة عدة قوى تؤثر عليه، هذه القوى تشمل وزنه، وقوة التلامس العمودية، وقوة الشد الناتجة عن الحبل، بالإضافة إلى قوة الاحتكاك التي تؤثر عكس قوة الشد، مما يؤدي إلى تحرك المجسم. أما بالنسبة للمجسم 2، فإن القوى المؤثرة عليه تقتصر على وزنه وقوة الشد في الحبل. بمجرد إنشاء مخطط الجسم الحر، يمكن تطبيق القانون الثاني لنيوتن على المجسمين. من خلال هذا التطبيق، يمكن استنباط معادلة تعبر عن القوة المحصلة المؤثرة على النظام. ستتضمن هذه المعادلة كتلة كلا من المجسمين، وتسارع النظام، والقوى المؤثرة على كل مجسم. بمجرد الحصول على المعادلة، يمكن استخدام العمليات الجبرية لإعادة ترتيب الحدود وحساب مقدار تسارع النظام. ستكون النتيجة قيمة عددية تمثل كيفية تصرف النظام تحت تأثير القوى المعطاة. لا يمكن المبالغة في أهمية مخطط الجسم الحر في هذه الحالة. فهو يوفر تمثيلًا واضحًا ومختصرًا للقوى المؤثرة، مما يسهل بشكل كبير عملية حساب تسارع النظام بدقة. بدون هذه الأداة، سيكون من الصعب فهم وتحليل سلوك المجسمات والقوى المؤثرة عليها.</div>

عندما يتعلق الأمر بدراسة سلوك الكائنات في الميكانيكا ، فإن أحد أهم الأدوات المتاحة هو مخطط الجسم الحر. ضع في اعتبارك ...

Education

JoVE Core

Mechanical Engineering

الهندسة الميكانيكية

Unit 1

الوحدة الأولى

Equilibrium of a Particle

اتزان الجسيم

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

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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Free-Body Diagram for Two-Block Motion

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