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

Rozważmy układ dwóch bloków połączonych bezmasowym sznurkiem nad kołem pasowym. Blok 1 ślizga się po stole ciągniętym przez blok 2, gdy spada pod wpływem grawitacji. 
Przyspieszenie układu można wyznaczyć, obliczając siłę wypadkową działającą na układ.
Diagram swobodnego ciała dla tego systemu można narysować, przedstawiając dwa bloki wraz z ich konturem. W tym przypadku bloki są uważane za izolowane.
Działające na nie siły zewnętrzne są identyfikowane i reprezentowane przez strzałki wektorowe.
Siły działające na blok 1 to jego waga, siła normalna, siła naciągu powodowana przez linę oraz siła tarcia przeciwstawna sile naciągu powodującej ruch.
Podobnie siły działające na blok 2 to jego ciężar i siła rozciągająca.
Stosując drugą zasadę dynamiki Newtona do bloków, można wyprowadzić równanie siły wypadkowej.
Korzystając z operacji algebraicznej i przestawiając wyrazy, można uzyskać wielkość przyspieszenia układu.

<ol>
	<li>Hibbeler, R.C. (2016). Mechanika inżynierska \u2012 Statyka i dynamika. Hoboken, New Jersey: Pearson Prentice Hall. Strona 89</li>
	<li>Piwo, F.P.; Johnston, E.R.; Mazurek, D.F.; Cromwell, PJ i Self, BP (2019). Mechanika wektorowa dla inżynierów \u2012 Statyka i dynamika. Nowy Jork: McGraw-Hill. Strony 171-172</li>
</ol>

kroki do diagramu ciała swobodnego

Kiedy chodzi o badanie zachowania obiektów w mechanice, jednym z kluczowych narzędzi jest diagram ciała swobodnego. Przyjrzyjmy się prostemu przykładowi systemu dwóch bloków połączonych bezmasowym sznurkiem poprzez nierozciągliwą, nieobciążoną reakcyjnie rolkę. Blok 1 przesuwa się po stole, pociągany przez blok 2, który opada pod wpływem grawitacji.

Aby obliczyć przyspieszenie systemu, konieczne jest najpierw obliczenie siły netto działającej na system. W tym celu można utworzyć diagram ciała swobodnego, który przedstawia dwa bloki jako jeden izolowany system, oddzielony od otoczenia. Siły zewnętrzne są następnie identyfikowane i przedstawiane za pomocą strzałek wektorowych na diagramie.

Przyjrzyjmy się blokowi 1, na którego działa kilka sił. Są to: jego masa, siła normalna, siła napięcia sznurka i siła tarcia, która przeciwdziała siłom napięcia i powoduje ruch. Dla bloku 2 działa tylko jego masa i siły napięcia.

Po stworzeniu diagramu ciała swobodnego można zastosować drugie prawo dynamiki Newtona do bloków. Dzięki temu można uzyskać równanie dla siły netto działającej na system. Równanie to będzie zawierało masy bloków, przyspieszenie systemu i siły działające na każdy blok.

Mając równanie, można zastosować operacje algebraiczne, aby przekształcić wyrazy i obliczyć wartość przyspieszenia systemu. Wynikiem będzie wartość liczbową, która reprezentuje zachowanie systemu pod wpływem określonych sił.

Nie można przecenić znaczenia diagramu ciała swobodnego w tej sytuacji. Daje on jasne i zwięzłe przedstawienie sił występujących w systemie, umożliwiając tym samym łatwiejsze i bardziej dokładne obliczenie przyspieszenia systemu. Bez tego narzędzia byłoby o wiele trudniej zrozumieć i analizować zachowanie bloków oraz siły działające na nie.

Kroki do diagramu ciała swobodnego

Jeśli chodzi o badanie zachowania obiektów w mechanice, jednym z najważniejszych dostępnych narzędzi jest diagram swobodnego ciała. Rozważ prosty ...

Education

JoVE Core

Mechanical Engineering

Inżynieria mechaniczna

Unit 1

Jednostka 1

Equilibrium of a Particle

Równowaga punktu materialnego

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

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

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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

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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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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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