Name: earth's spin and apparent weight
Uploaded: 2023-04-30T11:06:14.000Z
Duration: 1 min 28 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Weather and Climate

3.3.9-12.E

Apparent Weight and the Earth's Rotation

Consideremos un objeto de masa m suspendido de una escala de resorte unida a un soporte rígido en el ecuador de la Tierra. La lectura de la escala es el peso aparente del objeto mg', igual a la magnitud de la fuerza de tracción Ft en el resorte.
Si la Tierra fuera un cuerpo que no gira, la fuerza de tensión sería igual a la fuerza gravitacional Fg que actúa sobre el objeto, manteniéndolo en equilibrio.
Recordemos que la magnitud de la fuerza gravitacional es el peso real mg del objeto.
Sin embargo, dado que la Tierra gira alrededor de un eje que pasa a través de sus polos, el objeto en el ecuador describe un círculo alrededor del eje de rotación de la Tierra. Por lo tanto, tiene una aceleración centrípeta dirigida hacia el centro de la Tierra.
Por lo tanto, las fuerzas que actúan sobre el objeto son la fuerza gravitacional dirigida hacia el centro de la Tierra, la fuerza de tensión en el resorte dirigida lejos del centro de la Tierra y la fuerza centrípeta dirigida hacia el eje de rotación.
Por lo tanto, el peso aparente es igual al peso real menos la fuerza centrípeta. En los polos, la fuerza centrípeta sobre el objeto es cero, lo que implica que mg' es igual a mg.

peso aparente y la rotación de la tierra

Dado que todos los objetos en la superficie de la Tierra se mueven en un círculo cada 24 horas, debe haber una fuerza centrípeta neta en cada objeto, dirigida hacia el centro de ese círculo. Los puntos de los polos norte y sur son la única excepción a esta regla. Para un objeto en el ecuador de la Tierra, la fuerza centrípeta neta que cuenta para su rotación es la atracción de la Tierra hacia su centro, o el peso menos la fuerza normal que evita que se inserte en la superficie de la Tierra. Esta fuerza, llamada peso aparente, es por lo tanto el peso del objeto menos la fuerza centrípeta. La fuerza centrípeta es proporcional al radio de la Tierra y al cuadrado de la velocidad angular de la Tierra. La velocidad angular es relativamente pequeña; por lo tanto, la fuerza centrípeta, que también es la diferencia entre los pesos real y aparente, es bastante pequeña. En el ecuador, el peso aparente de un objeto es solo un 0.34% menos que su peso real, una corrección pequeña. Podemos entender aún más esta corrección menor considerando cómo de rápido tendría que rotar la Tierra para que todos los objetos en el ecuador se sientan sin peso debido a la rotación de la Tierra. Los cálculos implican que el período orbital de la Tierra, que es de 24 horas, tendría que ser solo de 84 minutos en su lugar. Este texto está adaptado de <a href="https://openstax.org/books/university-physics-volume-1/pages/13-2-gravitation-near-earths-surface">Openstax, University Physics Volume 1, Section 13.2: Gravitation Near Earth's Surface.</a>

Peso aparente y la rotación de la Tierra

Dado que todos los objetos en la superficie de la Tierra se mueven a través de un círculo cada 24 horas, debe haber una fuerza centrípeta neta en cada objeto, dirigida hacia ...

Education

Educación

JoVE Core

Physics

Física

Unit 1

Unidad 1

Gravitation

Gravitación

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

earth's spin and apparent weight

Earth’s spin changes how weight is measured on the surface. Because the Earth turns once every 24 hours, objects on the surface move in a circle. That motion requires a net centripetal force, which points toward the center of the circle. The north and south poles are the only exception.

At the equator, the force that provides this inward pull comes from Earth’s gravity. It is the difference between an object’s true weight and the normal force from the ground. The normal force is the support force that keeps an object from sinking through the surface. This difference is called the apparent weight.

The centripetal force depends on Earth’s radius and the square of its angular speed, or rotation rate. Earth’s angular speed is small, so the centripetal force is also small. At the equator, apparent weight is only 0.34% less than true weight. That makes the correction tiny in everyday life.

The size of this effect also shows why Earth does not make objects feel weightless from its rotation. For that to happen at the equator, Earth would need to spin much faster. The calculations show that the day would have to be only 84 minutes long instead of 24 hours.

Earth's Spin and Apparent Weight

gravitation

Newton’s Law Behind Planet Motion

Newton’s law of gravitation links falling objects, the Moon’s orbit, and planetary motion. Before Newton, many people thought the sky and Earth followed different laws. Kepler later described the three laws of planetary motion, but their connection to a deeper force was still unclear. Isaac Newton made that connection in 1665 to 1666. He showed that the same phenomenon explains why objects fall to Earth and why the Moon moves around Earth. He also found that the Moon’s centripetal acceleration...

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gravitation between spherically symmetric masses

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reduced mass coordinates: isolated two-body problem

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acceleration due to gravity on earth

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acceleration due to gravity on other planets

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Measuring Gravity on Distant Planets

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apparent weight and the earth's rotation

Earth’s spin changes how weight is measured on the surface. Because the Earth turns once every 24 hours, objects on the surface move in a circle. That motion requires a net centripetal force, which points toward the center of the circle. The north and south poles are the only exception. At the equator, the force that provides this inward pull comes from Earth’s gravity. It is the difference between an object’s true weight and the normal force from the ground. The normal force is the support...

variation in acceleration due to gravity near the earth's surface

variation-in-acceleration-due-to-gravity-near-the-earth-s-surface

How Earth’s Shape Affects Apparent Weight

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escape velocity

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circular orbits and critical velocity for satellites

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Orbital Speed and Period in Circular Paths

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Satellite Orbits and Energy in Space

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Planet Orbits as Ellipses

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kepler's second law of planetary motion

Kepler's Equal-Area Planet Motion

Kepler's second law explains how a planet moves faster and slower in its orbit around the Sun. Johannes Kepler, a German astronomer and mathematician in the early 17th century, developed three laws for planetary motion. His first law says that planets travel in elliptical orbits, with the Sun at one focus of the ellipse. Because the planet-Sun distance changes during the orbit, the planet does not move at the same speed all the time. In an elliptical orbit, the total energy of the planet is...

kepler's third law of planetary motion

Kepler’s Planet Distance Law

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tidal forces

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schwarzschild radius and event horizon

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principle of equivalence

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space-time curvature and the general theory of relativity

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Einstein’s Gravity and Mercury’s Orbit

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key terms and concepts

Learn how Earth’s rotation creates centripetal force, why apparent weight is slightly lower at the equator, and why the effect is very small.

Earth's Spin and Apparent Weight | JoVE K12

physics

JoVE Core Física presenta la teoría y la aplicación de conceptos físicos fundamentales, como la cinemática, dinámica, mecánica de fluidos, estática, ondas y acústica, mediante animaciones audiovisuales concisas y fáciles de entender. Además, los vídeos de científicos en acción muestran la aplicación de los conceptos relacionados en experimentos de investigación clásicos y originales, realizados en laboratorios de todo el mundo.

Louisiana Student Standards for Science

High School

Earth Science

Earth’s Systems

HS-ESS2-4

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Forces, Momentum And Motion

Gravitational force and fields

Virginia  Standards of Learning

HIgh School

ES.3

ES.3.b

PH.3

PH.3.b

Florida Department of Education

SC.912.E.5

SC.912.E.5.10

SC.912.E.5.11

Texas Essential Knowledge and Skills

PHYS.5

PHYS.5.H

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

Earth and Space Science (ESS)

Earth’s Place in the Universe

E-ESS1-6.

new-york-state-science-learning-standards

New York State Science Learning Standards

Physical Science

HS. Forces and Interactions

HS-PS2-4.

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3.3.9-12.S

Earth's Spin and Apparent Weight

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