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

يسمى التمثيل المرئي لجميع القوى المؤثرة على الجسيم بمخطط الجسم الحر أو مخطط القوة. يحول المشكلات المعقدة إلى تمثيلات بسيطة.
في مخطط الجسم الحر ، يشير اتجاه الأسهم إلى اتجاه القوى ، بينما يمثل طول الأسهم حجم القوى.
ضع في اعتبارك عربة ثابتة يتم تكديس صندوقين من الورق المقوى.
هنا ، يمكن افتراض أن النظامين المعنيين ، المربع الأول والمربع الثاني ، نظامان معزولان ويمكن تمثيلهما باستخدام مخطط الجسم الحر في شكل مخطط بسيط أو نقطة.
القوى المؤثرة على المربع الأول هي قوة الجاذبية ، التي تحدد وزنها ، والقوة العادية المضادة للموازنة الناتجة عن المربع الثاني.
وبالمثل ، فإن القوى الموجودة على الصندوق الثاني هي وزنها ، والقوة العادية الناتجة عن العربة ، ووزن الصندوق الأول.
تلعب مخططات الجسم الحر دورا أساسيا في عملية حل المشكلات كانتقال من موقف فيزيائي معين إلى معادلة رياضية مجردة في الميكانيكا.

<ol>
	<li>هيبلر ، آر سي (2016). الميكانيكا الهندسية - الإحصاء والديناميكيات. هوبوكين ، نيو جيرسي: قاعة بيرسون برنتيس. ص 88</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 170-171</li>
</ol>

مخطط الجسم الحر.

<div style="direction:rtl">في الميكانيكا، يُعد فهم حركة الأجسام أمرًا ضروريًا، وأحد الأدوات التي تساعد في فهم هذه الحركة هو مخطط الجسم الحر. وهو تمثيل بياني بسيط ولكنه فعال، حيث يُظهر بشكل موجز جميع القوى المؤثرة على جسم معين. يمكن استخدام مخطط الجسم الحر لتمثيل جسم ثابت أو متحرك، ويُستخدم في الميكانيكا لشرح مسببات حركة الجسم. يعمل مخطط الجسم الحر على تحويل المشكلة المعقدة إلى تمثيل بسيط، مما يسهل فهم القوى الأساسية المؤثرة على الجسم، وبالتالي التوصل إلى معادلة رياضية. في كثير من الحالات، قد تكون المعادلة معقدة للغاية لولا استخدام مخططات الجسم الحر. لإنشاء مخطط جسم حر، ابدأ بتحديد الجسم أو النظام قيد الدراسة، ثم قم بعزله عن محيطه ورسمه كنقطة أو مخطط بسيط. بعد ذلك، مثل جميع القوى الخارجية الأساسية المؤثرة على الجسم أو النظام باستخدام أسهم. يوضح اتجاه الأسهم اتجاه القوة، بينما يعبر طول الأسهم عن مقدار القوة. من المهم ملاحظة أن مخطط الجسم الحر لا يمثل السرعة أو التسارع بشكل مباشر، ولكنه يسمح باستنتاجهما من القوى المؤثرة على الجسم. تشمل بعض أنواع القوى الشائعة التي يمكن تمثيلها في مخطط الجسم الحر: الوزن، القوة العمودية، قوة الشد، قوة الاحتكاك، والقوة المؤثرة. الوزن: هو قوة الجاذبية المؤثرة على الجسم، ويتم تمثيله عادةً بسهم متجه نحو الأسفل. القوة العمودية: هي القوة الناتجة عن تلامس جسمين معًا، وتعمل في الاتجاه المعاكس لوزن الجسم. قوة الشد: يتم التعبير عنها عادةً بسهم يشير بعيدًا عن الجسم في اتجاه القوة. قوةالاحتكاك: هي القوة التي تقاوم الانزلاق بين الأسطح المتلامسة. اخيرا ، القوة المؤثرة: تشير إلى القوة التي يطبقها عامل خارجي على الجسم، مثل الدفع أو السحب، ويتم تمثيلها بسهم يشير في اتجاه القوة. يمكن اعتبار عربة ثابتة وُضِع عليها صندوقان من الورق المقوى كنظامين منفصلين يمكن تمثيلهما باستخدام مخطط الجسم الحر. تؤثر على الصندوق الأول قوتان رئيسيتان: قوة الجاذبية، التي تحدد وزنه، والقوة العمودية المعاكسة الناتجة عن الصندوق الثاني. وبالمثل، تؤثر على الصندوق الثاني ثلاث قوى: وزنه الذاتي الناتج عن الجاذبية، والقوة العمودية التي تبذلها العربة لدعمه، بالإضافة إلى القوة العمودية الناتجة عن وزن الصندوق الأول.</div>

في الميكانيكا ، يعد فهم حركة الأشياء أمرا ضروريا ، وإحدى الأدوات التي تساعد في حل هذه المشكلة هي مخطط الجسم الحر. إنه بسيط ولكن ...

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 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

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HS-PS2-6

Free-Body Diagrams for Force Analysis

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