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

הייצוג החזותי של כל הכוחות הפועלים על החלקיק נקרא דיאגרמת גוף חופשי או דיאגרמת כוח. הוא הופך בעיות מורכבות לייצוגים פשוטים.
בדיאגרמת גוף חופשי, כיוון החצים מציין את כיוון הכוחות, בעוד אורך החצים מייצג את גודל הכוחות.
חשבו על עגלה נייחת שעליה נערמים שתי קופסאות קרטון.
כאן, ניתן להניח ששתי מערכות העניין, תיבה אחת ותיבה שתיים, הן מערכות מבודדות וניתן לייצג אותן באמצעות דיאגרמת גוף חופשי בצורה של מתאר פשוט או נקודה.
הכוחות הפועלים בתיבה הראשונה הם כוח הכבידה, המגדיר את משקלה, והכוח הנורמלי המאזן הנגדי הנובע מהתיבה השנייה.
באופן דומה, הכוחות בתיבה שתיים הם משקלה שלה, הכוח הנורמלי הנובע מהעגלה, ומשקלה של התיבה הראשונה.
דיאגרמות גוף חופשי ממלאות חלק אינטגרלי בתהליך פתרון הבעיות כמעבר ממצב פיזיקלי מסוים למשוואה מתמטית מופשטת במכניקה.

<ol>
	<li>היבלר, R.C. (2016). מכניקה הנדסית - סטטיקה ודינמיקה. הובוקן, ניו ג'רזי: אולם פירסון פרנטיס. עמ' 88</li>
	<li>באר, פ"פ; ג'ונסטון, א.ר.; מזורק, ד"ו; קרומוול, פי ג'יי ועצמי, ב. (2019). מכניקה וקטורית למהנדסים - סטטיקה ודינמיקה. ניו יורק: מקגרו-היל. עמ' 170-171</li>
</ol>

דיאגרמת גוף חופשי

<div style="direction:rtl">במכניקה, הבנת התנועה של עצמים היא חיונית, וכלי אחד שעוזר לפתור בעיה זו הוא דיאגרמת הגוף החופשי. זהו ייצוג גרפי פשוט אך רב עוצמה המייצג בתמציתיות את כל הכוחות הפועלים על אובייקט. דיאגרמת גוף חופשי יכולה לייצג עצם נייח או נע, והיא משמשת במכניקה כדי להסביר את הסיבה לתנועת עצם. דיאגרמת גוף חופשי הופכת בעיה מורכבת לייצוג פשוט, מה שמקל על הבנת הכוחות החיוניים הפועלים על עצם, מה שמוביל למשוואה מתמטית. במקרים רבים, המשוואה תהיה מורכבת ביותר לגזירה מבלי להשתמש בדיאגרמות גוף חופשי. כדי ליצור דיאגרמת גוף חופשי, התחל בבחירת האובייקט או המערכת הנבדקת, בידודם מסביבתו ושרטוטם כנקודה או כמתאר פשוט. לאחר מכן, ייצג את כל הכוחות החיצוניים החיוניים הפועלים על האובייקט או מערכת העניין באמצעות חיצים. כיוון החצים מייצג את כיוון הכוח, בעוד שאורך החצים מתאר את גודל הכוח. חשוב לציין שבדיאגרמת גוף חופשי, מהירות ותאוצה אינן מיוצגות, אלא ניתן להסיק מהכוחות המופעלים על העצם. כמה סוגים נפוצים של כוחות שניתן לייצג בתרשים גוף חופשי כוללים משקל, כוח נורמלי, מתח, חיכוך וכוח מופעל. משקל מתייחס לכוח הכבידה הפועל על העצם, המיוצג בדרך כלל על ידי חץ המצביע כלפי מטה. כוח רגיל הוא הכוח בין שני עצמים כאשר הם באים במגע זה עם זה; כוח זה פועל בכיוון ההפוך למשקל האובייקט. המתח מיוצג בדרך כלל על ידי חץ המצביע הרחק מהאובייקט בכיוון הכוח, וחיכוך הוא הכוח המתנגד לגלישה בין משטחים. לבסוף, כוח מופעל מתייחס לכוח המופעל על האובייקט על ידי גורם חיצוני, כגון דחיפה או משיכה. הכוחות המופעלים מיוצגים על ידי חץ המצביע לכיוון הכוח. חשבו על עגלה נייחת, שעליה מוערמות שתי קופסאות קרטון. ניתן להניח ששתי מערכות העניין, תיבה אחת ותיבה שתיים, הן מערכות מבודדות וניתן לייצג אותן באמצעות דיאגרמת גוף חופשי. הכוחות הפועלים על תיבה אחת הם כוח הכבידה, המגדיר את משקלה, והכוח הנורמלי המאזן הנגדי כתוצאה מתיבה שניה. באופן דומה, הכוחות על תיבה 2 הם משקלה, הכוח הרגיל הנובע מהעגלה ומשקלה של תיבה אחת.</div>

במכניקה, הבנת התנועה של אובייקטים היא חיונית, וכלי אחד המסייע לפתור בעיה זו הוא דיאגרמת הגוף החופשי. זה פשוט אבל ...

Education

JoVE Core

Mechanical Engineering

הנדסת מכונות

Unit 1

יחידה 1

Equilibrium of a Particle

שיווי משקל של חלקיק

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

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

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

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Free-Body Diagrams for Force Analysis

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