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

La rappresentazione visiva di tutte le forze che agiscono sulla particella è chiamata diagramma di corpo libero o diagramma di forza. Trasforma problemi complessi in semplici rappresentazioni.
In un diagramma a corpo libero, la direzione delle frecce indica la direzione delle forze, mentre la lunghezza delle frecce rappresenta l'entità delle forze.
Considera un carrello fisso su cui sono impilate due scatole di cartone.
Qui, i due sistemi di interesse, scatola uno e scatola due, possono essere assunti come sistemi isolati e possono essere rappresentati utilizzando un diagramma di corpo libero sotto forma di un semplice contorno o di un punto.
Le forze che agiscono sulla scatola uno sono la forza gravitazionale, che ne definisce il peso, e la forza normale di controbilanciamento dovuta alla scatola due.
Allo stesso modo, le forze sulla scatola due sono il suo peso, la forza normale dovuta al carrello e il peso della scatola uno.
I diagrammi a corpo libero svolgono un ruolo fondamentale nel processo di risoluzione dei problemi come transizione da una specifica situazione fisica a un'equazione matematica astratta in meccanica.

<ol>
	<li>Hibbeler, R.C. (2016). Ingegneria Meccanica \u2012 Statica e Dinamica. Hoboken, New Jersey: Pearson Prentice Hall. pagine 88</li>
	<li>Birra, F.P.; Johnston, E.R.; Mazurek, D.F; Cromwell, P.J. e Self, B.P. (2019). Meccanica vettoriale per ingegneri \u2012 Statica e dinamica. New York: McGraw-Hill. pagine 170-171</li>
</ol>

diagramma di corpo libero

In meccanica, la comprensione del moto degli oggetti è essenziale, e uno strumento che aiuta a risolvere questo problema è il diagramma di corpo libero. È una rappresentazione grafica semplice ma potente che rappresenta in modo conciso tutte le forze che agiscono su un oggetto. Un diagramma del corpo libero può rappresentare un oggetto fermo o in movimento ed è utilizzato in meccanica per spiegare la causa del moto di un oggetto.

Esso trasforma un problema complesso in una rappresentazione semplice, rendendo facile comprendere le forze essenziali che agiscono su un oggetto, portando a un'equazione matematica. In molti casi, l'equazione sarebbe estremamente complessa da derivare senza l'uso di diagrammi di corpo libero. Per realizzare un diagramma di questo tipo, si inizia selezionando l'oggetto o il sistema sotto ispezione, isolandolo dal suo ambiente e disegnandolo come un punto o un semplice contorno. Successivamente, si rappresentano tutte le forze esterne essenziali che agiscono sull'oggetto o sul sistema di interesse con delle frecce. La direzione delle frecce rappresenta la direzione della forza, mentre la lunghezza delle frecce rappresenta l'entità della forza. È importante notare che in un diagramma di corpo libero, la velocità e l'accelerazione non sono rappresentate, ma possono essere dedotte dalle forze applicate sull'oggetto.

Alcuni tipi comuni di forze che possono trovarsi in un diagramma di corpo libero includono il peso, la forza normale, la tensione, l'attrito e la forza applicata. Il peso si riferisce alla forza di gravità che agisce sull'oggetto, di solito rappresentata da una freccia che punta verso il basso. La forza normale è la forza tra due oggetti quando entrano in contatto tra loro; questa forza agisce nella direzione opposta al peso dell'oggetto. La tensione è generalmente rappresentata da una freccia che punta lontano dall'oggetto nella direzione della forza, mentre l'attrito è la forza che contrasta lo scorrimento tra le superfici. Infine, la forza applicata si riferisce alla forza applicata all'oggetto da un agente esterno, come una spinta o una trazione. Le forze applicate sono rappresentate da una freccia che punta nella direzione della forza.

Considera un carrello fermo, sul quale sono impilate due scatole di cartone. I due sistemi di interesse, scatola uno e scatola due, possono essere considerati sistemi isolati e possono essere rappresentati utilizzando un diagramma del corpo libero. Le forze che agiscono sulla scatola uno sono la forza gravitazionale, che ne definisce il peso, e la forza normale di contro-bilanciamento dovuta alla scatola due. Allo stesso modo, le forze sulla scatola due sono il suo peso, la forza normale del carrello e il peso della scatola uno.

Diagramma di corpo libero

In meccanica, comprendere il movimento degli oggetti è essenziale e uno strumento che aiuta a risolvere questo problema è il diagramma di corpo libero. Si tratta di un semplice ma ...

Education

Didattica

JoVE Core

Mechanical Engineering

Ingegneria Meccanica

Unit 1

Unità 1

Equilibrium of a Particle

Equilibrio di una particella

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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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HS-PS2-6

Free-Body Diagrams for Force Analysis

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