Name: cutting pliers as a force-multiplying machine
Uploaded: 2023-09-22T11:49:25.000Z
Duration: 1 min 19 s
Channel: JoVE

K12 Standards

Arizona Science Standards

High School

Physical Science

HS.P3

HS.P3U2.7

Machines

As máquinas são estruturas feitas de membros multi-força móveis conectados por pinos que formam um sistema estabilizado para transmitir forças.
Considere um alicate de corte usado para cortar um fio aplicando forças em seu cabo.
Quando forças iguais e opostas são aplicadas nas alças do alicate de corte, isso faz com que as arestas de corte do alicate se juntem e apliquem forças de reação iguais e opostas no fio, que são maiores que as forças aplicadas.
A magnitude das forças exercidas no fio devido às forças aplicadas pode ser determinada desmontando o alicate de corte e desenhando um diagrama de corpo livre dos componentes do alicate de corte.
Ao tomar um momento sobre o pino pivô que mantém o alicate unido, uma relação pode ser estabelecida entre as forças aplicadas e de reação, que atuam à distância.
Da mesma forma, desenhando um diagrama de corpo livre para o pino pivô, os componentes da força interna no pino pivô podem ser determinados.

<ol>
	<li>Hibbeler, R.C. (2016). Engenharia Mecânica \u2012 Estática e Dinâmica. Hoboken, Nova Jersey: Pearson Prentice Hall. pág. 305</li>
	<li>Cerveja, F.P.; Johnston, E.R.; Mazurek, D.F; Cromwell, PJ e Self, BP (2019). Mecânica vetorial para engenheiros \u2012 estática e dinâmica. Nova Iorque: McGraw-Hill. pág. 107 - 348</li>
</ol>

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máquinas

As máquinas são estruturas complexas compostas por membros móveis conectados por pinos que trabalham juntos para transmitir forças. Um exemplo de máquina é o alicate de corte, que é usado para cortar fios aplicando forças em suas alças. Quando forças iguais e opostas são exercidas nas alças do alicate de corte, elas fazem com que as bordas de corte se aproximem e apliquem forças de reação iguais e opostas no fio, que são maiores do que as forças aplicadas.

Um diagrama de corpo livre dos componentes do alicate de corte é considerado para determinar a magnitude das forças atuando no fio devido às forças aplicadas.

<img alt="Figure 1" src="/files/ftp_upload/14293/14293_PT_Fig_1v2.svg" style="text-align: center; height: 350px;" />

A análise do momento em torno do pino do pivô que mantém o alicate junto pode ajudar a estabelecer uma relação direta entre a força aplicada F e a força de reação P, em relação às suas respectivas distâncias do pino do pivô.

<img alt="Equation 1" src="/files/ftp_upload/14293/14293_PT_Equation_1v2.svg" style="text-align: center; height: 30px;" />

Além disso, criando um diagrama de corpo livre para o pino do pivô, é possível determinar os componentes da força interna no ponto de pivô. Aplicando a condição de equilíbrio de forças horizontais, a força interna Ox é zero. Da mesma forma, aplicando a condição de equilíbrio de forças verticais, a força interna Oy é igual à soma da força aplicada F e da força de reação P.

Máquinas

As máquinas são estruturas complexas que consistem em membros multi-força móveis conectados por pinos que trabalham juntos para transmitir forças. Um exemplo de máquina ...

Education

JoVE Core

Mechanical Engineering

Engenharia Mecânica

Unit 1

Unidade 1

Structural Analysis

Análise Estrutural

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

cutting pliers as a force-multiplying machine

Cutting pliers are a machine that helps transmit force through movable, pin-connected members. In this example, the handles and cutting edges work together to cut wire by turning an input force into a larger output force at the jaws.

When equal and opposite forces are applied to the handles, the cutting edges move toward each other. They then apply equal and opposite reaction forces to the wire. These reaction forces are greater than the forces applied to the handles, which is why the wire can be cut.

A free-body diagram of the plier parts is used to find the size of the forces acting on the wire. Taking the moment about the pivot pin, the pin that holds the pliers together, gives a direct link between the applied force F and the reaction force P. That relationship depends on how far each force acts from the pivot pin.

A free-body diagram of the pivot pin also shows the internal force at that point. Using horizontal force equilibrium, the internal force O x is zero. Using vertical force equilibrium, the internal force O y equals the sum of the applied force F and the reaction force P.

Cutting Pliers as a Force-Multiplying Machine

cutting-pliers-as-a-force-multiplying-machine

introduction to structures

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method of sections: problem solving ii

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space trusses

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machines

Cutting pliers are a machine that helps transmit force through movable, pin-connected members. In this example, the handles and cutting edges work together to cut wire by turning an input force into a larger output force at the jaws. When equal and opposite forces are applied to the handles, the cutting edges move toward each other. They then apply equal and opposite reaction forces to the wire. These reaction forces are greater than the forces applied to the handles, which is why the wire can...

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key terms and concepts

See how cutting pliers act as a machine, using a pivot pin, free-body diagrams, and force balance to produce a larger cutting force on wire.

Cutting Pliers as a Force-Multiplying Machine | JoVE K12

O JoVE Core Mechanical Engineering oferece vídeos animados concisos e de fácil compreensão que abrangem tópicos-chave como equilíbrio, forças, análise de treliças e mecânica estrutural. Explore suas aplicações no mundo real e observe esses conceitos em ação por meio de experimentos conduzidos por cientistas.

mechanical engineering

Georgia Standards of Excellence

9-12

SPS8.

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Cutting Pliers as a Force-Multiplying Machine

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