Name: work in force and motion
Uploaded: 2023-09-22T11:49:36.000Z
Duration: 1 min 14 s
Channel: JoVE

El trabajo se produce cuando una fuerza que actúa sobre un objeto lo desplaza. Es igual al producto de la componente escalar de la fuerza a lo largo de la dirección de desplazamiento.
Matemáticamente, el trabajo se puede dar como el producto escalonado de la fuerza aplicada y el desplazamiento del objeto.
La unidad de trabajo del SI es el julio. Un julio es el trabajo realizado cuando una fuerza de un newton desplaza un objeto en un metro.
Dado que el trabajo es una cantidad escalar, su magnitud puede ser positiva, negativa o cero dependiendo de la dirección de la fuerza en relación con el desplazamiento.

Considere el ejemplo de una grúa que levanta una carga hacia arriba. Aquí, la fuerza aplicada y los vectores de desplazamiento están alineados en la misma dirección, por lo que el trabajo realizado es positivo.

En otro ejemplo, cuando se aplican los frenos a un automóvil en movimiento, la fuerza de frenado actúa en la dirección opuesta al movimiento del automóvil. Aquí, el trabajo realizado es negativo.

Una polea sin fricción que levanta una carga a través de una cuerda inextensible sin masa no hace ningún trabajo, ya que la fuerza y el desplazamiento son perpendiculares.

<ol>
	<li>Hibbeler, R.C. (2016). Ingeniería Mecánica: Estática. Decimocuarta edición, Nueva Jersey: Pearson. Sección 11.1, págs. 581 y 582.</li>
	<li>Meriam, J.L., Kraige, L.G. y Bolton, J.N. (2016). Ingeniería Mecánica: Estática y Dinámica. Octava edición, Singapur: John Wiley & Sons. Sección 7.2, págs. 392 y 393.</li>
	<li>Beer, F.P., Johnston, E.R., Mazurek, D.F., Cornwell, P.J. y Self, B.P. (2016). Mecánica vectorial para ingenieros. Undécima Edición, Nueva York: McGraw-Hill Education. Sección 10.1A, págs. 575.</li>
</ol>

trabajo

El trabajo es un concepto fundamental de la ingeniería mecánica y tiene muchas aplicaciones. Comprender cómo se calcula el trabajo y los diferentes tipos de trabajo puede ayudarnos a entender mejor los procesos físicos y obtener conocimientos sobre problemas complejos. El trabajo se define como el resultado de una fuerza que actúa sobre un objeto, haciendo que se mueva a lo largo de la línea de acción de la fuerza. También se define como el proceso de transferir energía mediante la aplicación de una fuerza sobre un objeto, lo que resulta en su desplazamiento. Esta transferencia de energía es responsable del cambio de movimiento o posición del objeto. El trabajo se puede escribir como el producto de la fuerza y la componente del desplazamiento en la misma dirección, o alternativamente se puede escribir como el producto escalar de la fuerza aplicada y el desplazamiento del objeto. El sistema SI considera al julio como su unidad, lo cual es igual a realizar un newton de fuerza sobre un metro de desplazamiento. El tipo de trabajo realizado sobre un objeto depende de la dirección de la fuerza en relación con el desplazamiento. Si la fuerza aplicada y el desplazamiento son paralelos entre sí, el trabajo realizado es positivo y si son antiparalelos, el trabajo realizado es negativo. Cuando la fuerza aplicada y el desplazamiento son perpendiculares entre sí, el trabajo realizado es cero. Un ejemplo de trabajo positivo es cuando una grúa levanta una carga pesada, mediante la aplicación de una fuerza hacia arriba sobre la carga, esta se mueve con relación al nivel del suelo. El trabajo negativo ocurre, por ejemplo, cuando se aplican frenos a un automóvil en movimiento, las ruedas ejercen una fuerza en contra de su movimiento, lo que resulta en un trabajo negativo realizado sobre él. Algunas fuerzas, como las que actúan en puntos fijos o perpendiculares al desplazamiento, no realizan trabajo. Ejemplos incluyen la reacción en un pasador sin fricción cuando el cuerpo soportado gira alrededor de este, la fuerza de reacción que actúa sobre un cuerpo que se mueve sobre una superficie sin fricción, etc. Sin embargo, las fuerzas que realizan trabajo incluyen el peso de un cuerpo y la fuerza de fricción que actúa sobre un cuerpo que se mueve sobre una superficie rugosa. En algunos casos, la suma del trabajo realizado por múltiples fuerzas es cero. Por ejemplo, dos cuerpos rígidos conectados por un pasador sin fricción requieren fuerzas iguales pero opuestas para el movimiento, por lo que su trabajo combinado es cero. De manera similar, dos bloques conectados por una cuerda extensible tienen tensiones de igual magnitud pero signos opuestos, lo que da como resultado un trabajo cero. En general, comprender qué fuerzas producen trabajo y cómo calcular el trabajo puede proporcionar conocimientos útiles sobre problemas físicos complejos y permitirnos gestionar estos procesos de manera efectiva para obtener los resultados deseados.

Trabajo

El trabajo es un concepto fundamental de la ingeniería mecánica y tiene muchas aplicaciones. Comprender cómo se calcula el trabajo y los diferentes tipos de trabajo ...

Education

Educación

JoVE Core

Mechanical Engineering

Ingeniería Mecánica

Unit 1

Unidad 1

Virtual Work

Trabajo virtual

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

Work

work in force and motion

Work connects force, motion, and energy in mechanics. It happens when a force acts on an object and the object moves along the line of action of that force. Work can also be described as energy transfer caused by applying a force, which leads to a change in the object’s motion or position.

Work is calculated as the force multiplied by the part of the displacement in the same direction as the force. It can also be written as the dot product of the applied force and the object’s displacement. In the SI system, the unit of work is the joule. One joule is equal to one newton of force acting over one meter of displacement.

The direction of the force compared with the displacement tells us the type of work done. When the force and displacement are parallel, the work is positive. When they are anti-parallel, the work is negative. When the force and displacement are perpendicular, the work is zero.

A crane lifting a heavy load is an example of positive work. The crane applies an upward force, and the load moves upward. Brakes on a moving car show negative work. The wheels exert a force that opposes motion, so work is done against the car’s movement.

Some forces do no work. This includes forces acting at fixed points or forces perpendicular to displacement. Examples include the reaction at a frictionless pin when a body rotates about it, and the reaction force on a body moving on a frictionless surface. Forces that do work include the weight of a body and friction acting on a body moving on a rough surface.

In some systems, the total work done by multiple forces is zero. Two rigid bodies connected by a frictionless pin need equal and opposite forces for motion, so their combined work is zero. The same idea applies to two blocks connected by an extensible cord, where the tension forces have equal magnitude but opposite signs. Knowing which forces produce work helps explain physical processes and solve mechanical problems.

Work in Force and Motion

work

Work connects force, motion, and energy in mechanics. It happens when a force acts on an object and the object moves along the line of action of that force. Work can also be described as energy transfer caused by applying a force, which leads to a change in the object’s motion or position. Work is calculated as the force multiplied by the part of the displacement in the same direction as the force. It can also be written as the dot product of the applied force and the object’s displacement. In...

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key terms and concepts

Learn how work is calculated from force and displacement, why it can be positive, negative, or zero, and see real examples from cranes and brakes.

Work in Force and Motion | 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.

mechanical engineering

Work in Force and Motion

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