Name: why motion seems different in accelerating frames
Uploaded: 2023-04-30T10:54:29.000Z
Duration: 1 min 27 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Physical Science

Forces and Interactions

3.2.9-12.J

Non-inertial Frames of Reference

Erinnern wir uns daran, dass die Bezugssysteme, in denen die Newtonschen Gesetze gelten, als Inertialsysteme bekannt sind. Es gibt jedoch Bezugssysteme, die sich den Newtonschen Gesetzen widersetzen, die sogenannten nicht-inertialen Bezugssysteme.
Nicht-Inertialsysteme beschleunigen oder verlangsamen sich relativ zu den Inertialsystemen.
Wenn zum Beispiel ein Flugzeug abhebt, spüren die Passagiere eine Rückwärtskraft, die der Beschleunigung des Flugzeugs entgegengesetzt ist. Dies verstößt gegen das zweite Newtonsche Gesetz, nach dem Objekte in Richtung der äußeren Nettokraft beschleunigt werden.
In nicht-inertialen Systemen sind inertiale oder fiktive Kräfte, die keinen physikalischen Ursprung haben, notwendig, um die Bewegung von Objekten zu erklären. In der Mechanik ist es also bequemer, einen Inertialrahmen zu verwenden.
Im Idealfall ist ein an die Erde gebundenes Bezugssystem aufgrund seiner Umdrehung und Rotation nicht inertial. Die Kräfte, die durch die Erdrotation entstehen, sind bei kleinen mechanischen Bewegungen jedoch vernachlässigbar, wirken sich aber auf großräumige Bewegungen wie Windmuster aus.
Die fiktive Kraft in diesem Rahmen lenkt den Wind auf der Nordhalbkugel im Uhrzeigersinn und auf der Südhalbkugel gegen den Uhrzeigersinn ab.

Es wurden keine Interessenkonflikte angegeben.

nicht-inertiale referenzrahmene

Ein Referenzrahmen, das relativ zu einem inertialen Referenzrahmen beschleunigt oder verlangsamt wird, ist ein nicht-inertiales Referenzrahmen. Um dies zu verstehen, betrachten Sie, was das Starten eines Flugzeugs, das Abbiegen in einem Auto, das Fahren auf einem Karussell und die kreisförmige Bewegung eines tropischen Wirbelsturms gemeinsam haben. Alle diese Systeme beschleunigen, verlangsamen oder rotieren relativ zur Erde. Daher handelt es sich um nicht-inertiale Referenzrahmene. Alle diese Systeme zeigen träge Kräfte, die nur durch die Bewegung zu entstehen scheinen, da sich der Beobachtungsrahmen relativ zur Erde beschleunigt oder rotiert. Wir können diese Standpunkte versöhnen, indem wir die verwendeten Referenzrahmene untersuchen. Ein Physiker wählt dasjenige Referenzrahmen, das für die zu analysierende Situation am praktischsten ist. Physiker haben kein Problem damit, träge Kräfte und Newtons zweites Gesetz wie gewohnt zu berücksichtigen, wenn dies praktischer ist. Ähnlich werden nicht-inertiale (beschleunigte) Referenzrahmene verwendet, wenn dies hilfreich ist. Unterschiedliche Referenzrahmene müssen berücksichtigt werden, wenn beispielsweise die Bewegung eines Astronauten in einem Raumschiff, das sich mit Geschwindigkeiten nahe der Lichtgeschwindigkeit bewegt, diskutiert wird, da dies auf die spezielle Relativitätstheorie zutrifft.

Die Erde kann als inertialer Bezugspunkt mit wenig oder keinen Bedenken hinsichtlich der Auswirkungen, die durch ihre Rotation verursacht werden, verwendet werden. Es gibt jedoch solche Auswirkungen, zum Beispiel bei der Rotation von Wettersystemen. Aus der Sicht des Nordpols betrachtet dreht sich die Erde gegen den Uhrzeigersinn, und jede Bewegung auf der Nordhalbkugel der Erde erfährt eine Coriolis-Kraft nach rechts. Das Gegenteil geschieht auf der Südhalbkugel, wo die Kraft nach links zeigt. Da die Winkelgeschwindigkeit der Erde gering ist, ist die Coriolis-Kraft normalerweise vernachlässigbar, aber sie hat erhebliche Auswirkungen auf großräumige Bewegungen wie Windmuster. Die Coriolis-Kraft bewirkt, dass sich Hurrikans auf der Nordhalbkugel gegen den Uhrzeigersinn drehen, während sich tropische Wirbelstürme auf der Südhalbkugel im Uhrzeigersinn drehen.

Die Rotation von tropischen Wirbelstürmen und die Bahn eines Balles auf einem Karussell können ebenso gut durch Trägheit und die Rotation des darunter liegenden Systems erklärt werden. Wenn nicht-inertiale Referenzrahmene verwendet werden, müssen träge Kräfte wie die Coriolis-Kraft erfunden werden, um den gekrümmten Weg zu erklären. Es gibt keine erkennbare physikalische Quelle für diese trägen Kräfte. Wenn inertielle Referenzrahmene verwendet werden, erklärt die Trägheit den Weg und es gibt für jede Kraft eine identifizierbare Quelle. Wir können beide Ansichten verwenden, um die Natur zu beschreiben, aber eine Ansicht in einem inertialen Referenzrahmen ist einfacher, da alle Kräfte Ursprünge und Erklärungen haben.

Dieser Text ist angepasst von <a href="https://openstax.org/books/university-physics-volume-1/pages/5-6-common-forces">Openstax, University Physics Volume 1, Abschnitt 5.6: Gemeinsame Kräfte</a> und <a href="https://openstax.org/books/university-physics-volume-1/pages/6-3-centripetal-force">Abschnitt 6.3: Zentripetalkraft.</a>

Nicht-inertiale Referenzrahmene

Ein Bezugssystem, das relativ zu einem Inertialsystem beschleunigt oder abbremst, ist ein Nicht-Inertialsystem. Um dies zu verstehen, überlegen Sie, was beim Abheben in ...

Education

Lehre

JoVE Core

Physics

Physik

Unit 1

Einheit 1

Newton's Laws of Motion

Newtons Bewegungsgesetze

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

why motion seems different in accelerating frames

A non-inertial frame of reference is a frame that accelerates, decelerates, or rotates relative to an inertial frame. In these frames, motion can look unusual because the observer is moving with the system. That is why an airplane taking off, a car turning a corner, a merry-go-round, and a tropical cyclone can all be examples of non-inertial motion.

These situations can show inertial forces, which seem to appear because the frame itself is accelerating or rotating. The force does not come from a physical source in the usual sense. Instead, it is tied to the observer’s frame of reference.

Physicists choose the reference frame that is most useful for the problem being studied. They can use inertial frames and apply Newton’s second law in the usual way. They can also use non-inertial frames when that makes the description easier.

Different frames of reference matter in special cases, such as an astronaut in a spacecraft moving near the speed of light. This is important in the special theory of relativity. In many problems, the Earth is used as an inertial frame because its rotation causes little trouble.

Even so, Earth’s rotation does affect some motions. Viewed from above the North Pole, Earth rotates counterclockwise. Motion in the Northern Hemisphere then experiences a Coriolis force to the right, while the Southern Hemisphere experiences a force to the left.

Because Earth’s angular velocity is small, the Coriolis force is usually negligible. It still has major effects on large-scale motion, such as wind patterns. It helps explain why hurricanes in the Northern Hemisphere rotate counterclockwise and why tropical cyclones in the Southern Hemisphere rotate clockwise.

The path of a ball on a merry-go-round and the motion of a tropical cyclone can also be explained by inertia and by the rotation of the system underneath. When a non-inertial frame is used, inertial forces such as the Coriolis force must be added to explain the curved path. When an inertial frame is used, inertia explains the motion, and every force has a clear source. Both views can describe nature, but the inertial frame is usually simpler.

Why Motion Seems Different in Accelerating Frames

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Explore how accelerating, decelerating, and rotating frames change the way motion looks, from cars and merry-go-rounds to Coriolis force and hurricanes.

Why Motion Seems Different in Accelerating Frames | JoVE K12

physics

JoVE Core Physics introduces the theory and application of fundamental physics topics, including kinematics, dynamics, fluid mechanics, statics, waves, and acoustics, with concise and easy-to-understand animated videos. Additionally, the scientist-in-action videos demonstrate the application of related concepts in classical and original research experiments performed in today's laboratories worldwide.

Louisiana Student Standards for Science

High School

motion-and-stability-forces-and-interactions

Motion And Stability: Forces And Interactions

HS-PS2-2

HS-PS2-3

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Forces And Motion

Motion

Tennessee Academic Standards

Motion and Stability: Forces and Interactions

PHYS.PS2.14

Virginia  Standards of Learning

HIgh School

PS.8

PS.8.b

PH.3

PH.3.a

Next Generation Science Standards

Florida Department of Education

SC.912.P.12

SC.912.P.12.3

SC.912.P.12.8

SC.912.P.12.9

Texas Essential Knowledge and Skills

PHYS.5

PHYS.5.C

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Forces and Interactions

HS-PS2-1.

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3.2.9-12.K

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3.2.9-12.M

Why Motion Seems Different in Accelerating Frames

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