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

Stellen Sie sich ein System aus zwei Blöcken vor, die durch eine masselose Schnur über einer Riemenscheibe gekoppelt sind. Block 1 gleitet über einen Tisch, der von Block 2 gezogen wird, während er unter die Schwerkraft fällt. 
Die Beschleunigung des Systems kann durch Berechnung der Nettokraft auf das System abgeleitet werden.
Ein Freikörperdiagramm für dieses System kann gezeichnet werden, indem die beiden Blöcke mit ihrem Umriss dargestellt werden. Hier werden die Blöcke als isoliert betrachtet.
Die auf sie wirkenden äußeren Kräfte werden durch Vektorpfeile gekennzeichnet und dargestellt.
Die Kräfte auf Block 1 sind sein Gewicht, die Normalkraft, die Zugkraft durch das Seil und die Reibungskraft, die der Zugkraft entgegenwirkt, die die Bewegung verursacht.
In ähnlicher Weise sind die Kräfte, die auf Block 2 wirken, sein Gewicht und die Zugkraft.
Wendet man das zweite Newtonsche Bewegungsgesetz auf die Blöcke an, so kann eine Gleichung für die Nettokraft abgeleitet werden.
Mit Hilfe der algebraischen Operation und der Neuanordnung der Terme kann die Größe der Beschleunigung des Systems ermittelt werden.

<ol>
	<li>Hibbeler, R.C. (2016). Technische Mechanik \u2012 Statik und Dynamik. Hoboken, New Jersey: Pearson Prentice Hall. Seite 89</li>
	<li>Bier, F.P.; Johnston, E.R.; Mazurek, D.F.; Cromwell, P.J. und Self, B.P. (2019). Vektormechanik für Ingenieure \u2012 Statik und Dynamik. New York: McGraw-Hill. Seiten 171-172</li>
</ol>

schritte für freikörperdiagramm

Wenn es darum geht, das Verhalten von Objekten in der Mechanik zu studieren, ist eines der wichtigsten verfügbaren Werkzeuge das Freikörperdiagramm. Betrachten Sie ein einfaches Beispiel eines Systems aus zwei Blöcken, die durch eine masselose Schnur über eine reibungsfreie Umlenkrolle gekoppelt sind. Block 1 gleitet über einen Tisch, während Block 2 durch die Schwerkraft fällt. Um die Beschleunigung des Systems zu finden, ist es zunächst notwendig, die Nettokraft auf das System zu berechnen. Um dies zu erreichen, kann ein Freikörperdiagramm erstellt werden, um die beiden Blöcke darzustellen, die als ein isoliertes System von der Umgebung betrachtet werden. Die externen Kräfte werden dann identifiziert und durch Vektorpfeile auf dem Diagramm dargestellt. Wenn man sich Block 1 anschaut, wirken mehrere Kräfte auf ihn. Dazu gehören sein Gewicht, die Normalkraft, die Spannungskraft durch das Seil und die Reibungskraft, die der Spannungskraft entgegenwirkt und somit die Bewegung verursacht. Für Block 2 wirken nur sein Gewicht und die Spannungskräfte auf ihn. Sobald das Freikörperdiagramm erstellt wurde, ist es möglich, das zweite Newtonsche Bewegungsgesetz auf die Blöcke anzuwenden. Dadurch kann eine Gleichung für die Nettokraft auf das System abgeleitet werden. Diese Gleichung wird die Massen der Blöcke, die Beschleunigung des Systems und die auf jeden Block wirkenden Kräfte enthalten. Mit der Gleichung in der Hand ist es dann möglich, algebraische Operationen anzuwenden, um die Größenordnung der Beschleunigung des Systems zu ermitteln. Das Ergebnis wird ein numerischer Wert sein, der repräsentiert, wie sich das System unter den gegebenen Kräften verhalten wird. Die Bedeutung eines Freikörperdiagramms in dieser Situation kann nicht überbetont werden. Es liefert eine klare und prägnante Darstellung der Kräfte, die im Spiel sind, und ermöglicht so eine einfachere und genauere Berechnung der Beschleunigung des Systems. Ohne dieses Werkzeug wäre es viel schwieriger, das Verhalten der Blöcke und die auf sie wirkenden Kräfte zu verstehen und zu analysieren.

Schritte für Freikörperdiagramm

Wenn es darum geht, das Verhalten von Objekten in der Mechanik zu untersuchen, ist das Freikörperdiagramm eines der wichtigsten verfügbaren Werkzeuge. Betrachten Sie eine einfache ...

Education

Lehre

JoVE Core

Mechanical Engineering

Maschinenbau

Unit 1

Einheit 1

Equilibrium of a Particle

Gleichgewicht eines Teilchens

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

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...

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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...

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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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