Name: contact and field forces in physics
Uploaded: 2025-05-22T09:05:40.000Z
Duration: 1 min 9 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Physics

motion-and-stability-forces-and-interactions

Motion and Stability- Forces and Interactions

PS.Phy.2.1

Types of Forces

As forças são forças de contato ou de campo.
As forças de contato atuam quando os objetos estão se tocando, como (a) a força normal que impede que dois objetos ocupem o mesmo espaço, (b) a força de atrito que resiste ao deslizamento de objetos em uma superfície e (c) a tensão exercida por uma corda, arame, etc., sobre os objetos presos a ela.
Em contraste, as forças de campo não requerem contato físico. As quatro forças fundamentais do campo são interações nucleares gravitacionais, eletromagnéticas, fortes e fracas.
A força gravitacional é a interação entre objetos devido às suas massas.
A força eletromagnética é a interação entre partículas carregadas.
A força forte atua entre prótons e nêutrons dos átomos e os une, enquanto a força fraca é responsável pelo decaimento radioativo dos átomos.

Não há conflitos de interesse declarados.

tipos de forças

Na maioria das situações, as forças podem ser agrupadas em duas categorias: forças de contato e forças de campo. As forças de contato ocorrem como resultado do contato físico direto entre objetos. As forças de campo, no entanto, atuam sem a necessidade de contato físico entre objetos. Elas dependem da presença de um "campo" na região do espaço que envolve o corpo em consideração. Você pode pensar em um campo como uma propriedade do espaço, e que é detectável pelas forças que exerce. Os cientistas acreditam que existem apenas quatro campos de força fundamentais na natureza. São eles os campos gravitacional, eletromagnético, nuclear forte e nuclear fraco.

O campo gravitacional é responsável pelo peso de um corpo. As forças do campo eletromagnético incluem as da eletricidade estática e do magnetismo; elas também são responsáveis pela atração entre átomos na matéria agregada. Tanto os campos nucleares forte quanto o fraco são efetivos apenas em distâncias na escala de um núcleo atômico (10-15 m). A extensão deles é tão pequena que nenhum desses dois campos têm influência no mundo macroscópico da mecânica newtoniana.

As forças de contato são fundamentalmente eletromagnéticas. Quando uma fita adesiva gruda em um pedaço de papel, os átomos da fita se misturam com os do papel, gerando uma força eletromagnética resultante entre os dois objetos. No entanto, no contexto da mecânica newtoniana, a origem eletromagnética das forças de contato não é uma preocupação importante.

Este texto foi adaptado de <a href="https://openstax.org/books/university-physics-volume-1/pages/5-1-forces">Openstax, University Physics Volume 1, Section 5.1: Forces.</a>

Tipos de forças

Na maioria das situações, as forças podem ser agrupadas em duas categorias: forças de contato e forças de campo. As forças de contato ocorrem como resultado de forças físicas diretas ...

Education

JoVE Core

Física

Unit 1

Unidade 1

Newton's Laws of Motion

Leis do Movimento de Newton

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

contact and field forces in physics

Forces in physics are often grouped as contact forces and field forces. Contact forces happen when objects touch directly. Field forces act without direct physical contact. They come from a field, which is a region of space that can be detected by the force it exerts on a body.

Scientists describe four fundamental force fields in nature: gravitational, electromagnetic, strong nuclear, and weak nuclear. The gravitational field gives a body its weight. The electromagnetic field includes static electricity and magnetism, and it also helps hold atoms together in bulk matter.

The strong nuclear field and the weak force field act only over very short distances, about the size of an atomic nucleus, around 10−15 m. Because their range is so small, they do not affect the macroscopic world studied in Newtonian mechanics. Contact forces are also fundamentally electromagnetic. For example, tape sticks to paper because atoms in the tape and paper mix at the surface, creating a net electromagnetic force between the two objects.

Contact and Field Forces in Physics

force

Understanding Force in Motion

Force is a push or pull that acts on an object. It has both magnitude and direction, so force is a vector quantity. In everyday life, force appears when we open a door, walk down a street, lift a fork, or touch a baby's face. Forces also shape matter at the smallest scales. The atoms in our bodies are held together by electrical forces. The nucleus of an atom is held together by nuclear force, which is the strongest force known to us. The study of motion is called kinematics. Kinematics...

types of forces

Forces in physics are often grouped as contact forces and field forces. Contact forces happen when objects touch directly. Field forces act without direct physical contact. They come from a field, which is a region of space that can be detected by the force it exerts on a body. Scientists describe four fundamental force fields in nature: gravitational, electromagnetic, strong nuclear, and weak nuclear. The gravitational field gives a body its weight. The electromagnetic field includes static...

newton's first law: introduction

Newton's First Law and Inertia

Newton's first law of motion explains inertia and how forces change motion. Motion can be striking to observe, from a dolphin jumping from water to a bird in flight or a satellite moving in orbit. The study of motion is kinematics, which describes velocity and acceleration. Dynamics goes further by examining the forces that affect moving objects and systems. Newton's laws of motion are the foundation of dynamics. They are simple in form, but they describe a wide range of natural behavior.

newton's first law: application

Newton's First Law and Friction

Newton's first law explains why friction changes an object's motion. It says that an object at rest stays at rest, and an object in motion keeps moving unless a net external force acts on it. A net external force is the overall force from outside the object that causes a change in velocity, meaning a change in speed or direction. This idea gives a cause-and-effect reason for motion, rather than just describing what we see. Galileo first developed the idea behind the first law of motion, and...

internal and external forces

External Forces and Motion Changes

External forces and motion changes are linked in Newton’s first law. A net external force causes a change in motion. External forces act on an object or system from outside that object or system. Internal forces come from inside the system of interest. They act on one part of an object and are exerted by another part of the same object. These forces do not cause acceleration when the whole system is studied. When analyzing motion, the internal forces are ignored. Instead, only the external...

newton's second law

Force, Mass, and Acceleration

Newton's second law connects net force, mass, and acceleration. It explains how an object's motion changes when external forces act on it. The law gives a clear cause-and-effect link that can be used to make calculations. All external forces on a system are added together to find the net force, or F net. A larger net external force produces a larger acceleration. The acceleration points in the same direction as the net force. Mass also affects the result. A larger mass means more inertia, so...

mass and weight

Weight Changes, Mass Stays Constant

Mass and weight are related, but they are not the same. In physics, weight is the pull of the Earth on an object. It depends on how far the object is from the center of the Earth. Mass is the amount of matter in an object, and it does not change with location. Everyday language can make this difference confusing. Medical records often list body weight in kilograms, even though the correct force unit is the newton. That can make mass and weight seem interchangeable. In physics, however, they...

weightlessness

Weightlessness in Free Fall

Weightlessness happens when contact forces disappear, even though gravity is still present. In physics, an object in free fall has only gravity acting on it. If the net external force on the object is its weight, the object is accelerating toward the center of the Earth. Galileo showed that, without air resistance, all objects fall with the same acceleration g. On Earth, falling objects are never truly in free fall because air always pushes upward with some resistance force. That is why real...

apparent weight

Scale Readings in Motion and Water

Scale readings can change when an object is moving or submerged in water. The force we call true weight is the gravitational force acting on an object. When motion or fluid forces are present, the reading can differ from that true weight. In water, this changed reading is called apparent weight, and it equals true weight minus the buoyant force. A bathroom scale in an elevator shows how this works. At rest, the scale reads the force the person pushes downward on it. The only forces on the...

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newton's third law: introduction

Newton's Third Law in Force Pairs

Newton's third law explains how force pairs work in motion and interactions. When one body exerts a force on a second body, the first body experiences a force that is equal in magnitude and opposite in direction. A simple example is a person pushing on a wall. The wall pushes back on the person with an equal and opposite force. This is why Newton's third law is often described as action and reaction, where the action is the force exerted and the reaction is the force experienced afterward. <br...

newton's third law: examples

Newton's Third Law in Motion

Newton's third law explains how forces come in pairs during motion. It says that every action has an equal and opposite reaction. In these examples, the two forces act on different systems, so they do not cancel each other out. A swimmer pushing off the side of a pool shows this clearly. The swimmer pushes against the wall with their feet and then accelerates in the opposite direction. The wall pushes back with an equal and opposite force. If the swimmer is the system of interest, the wall's...

drawing free-body diagrams: rules

Free-Body Diagrams for Newton’s Laws

Free-body diagrams help students map the forces acting on an object in physics. They are used often when studying and applying Newton’s laws of motion. A clear diagram makes it easier to analyze a system before solving for motion. Start by drawing the object under consideration. If the object is treated like a particle, show it as a point and place that point at the origin of an x-y coordinate system. Then add every force that acts on the object as a vector. Do not include the net force on the...

free body diagrams: examples

Free Body Diagram Force Examples

Free body diagrams show the external forces acting on an object or system. The object is drawn as a single isolated point, or free body, so the forces are easier to analyze. Only forces that come from outside the object or system are included. These forces are shown as vectors pointing away from the free body. A person sitting on a chair is a simple example. The free-body diagram has two forces. The chair exerts an upward normal force, and gravity pulls downward with the weight. A rocket sled...

inertial frames of reference

Newton's First Law and Reference Frames

Newton's first law helps identify inertial reference frames. An inertial reference frame is one in which Newton's first law holds true. In that frame, an object with no net force moves at constant velocity. A key idea is that any frame moving at constant velocity relative to an inertial frame is also inertial. For that reason, inertial frames can be found by comparing motion from one frame to another. The laws of physics do not give one inertial frame special status over another. In nature, a...

non-inertial frames of reference

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...

centrifugal force

Rotating Frames and Pseudo Forces

Pseudo forces, also called fictitious forces, appear in a rotating frame of reference when compared with an inertial frame. They are not real forces. Instead, they are mathematical tools that help make Newton&amp;#39;s laws of motion easier to use in a non-inertial frame. Common examples include centrifugal, Coriolis, and Euler forces. These forces matter in mechanics, astrophysics, and fluid dynamics. In these areas, motion is often described from a frame that is not inertial. That is why...

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key terms and concepts

Learn how contact forces and field forces differ, and how gravitational, electromagnetic, strong nuclear, and weak nuclear fields shape motion and matter.

Contact and Field Forces in Physics | JoVE K12

physics

JoVE Core - Fisica apresenta a teoria e a aplicação de tópicos fundamentais da física, incluindo cinemática, dinâmica, mecânica dos fluidos, estática, ondas e acústica, com vídeos animados concisos e de fácil compreensão. Além disso, os vídeos de cientistas em ação demonstram a aplicação de conceitos relacionados em experimentos de pesquisa clássica e original realizados nos laboratórios de todo o mundo hoje em dia.

Pennsylvania State Academic Standards

Physical Science

Structure and Properties of Matter

3.2.9-12.A

3.2.9-12.B

3.2.9-12.N

Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-1

HS-PS1-3

Motion And Stability: Forces And Interactions

HS-PS2-6

HS-PS2-4

HS-PS2-5

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Forces And Motion

Forces

Forces, Momentum And Motion

newton-s-laws-applied-to-complex-problems

Newton's laws applied to complex problems

Friction force (static and kinetic)

Air resistance and drag

Forces in two dimensions

Tennessee Academic Standards

Motion and Stability: Forces and Interactions

PHYS.PS2.4

Energy

PHYS.PS3.9

Virginia  Standards of Learning

HIgh School

PS.8

PS.8.b

PH.3

PH.3.a

Alabama Course of Study Science

waves-and-their-applications-in-technologies-for-information-transfer

Waves and Their Applications in Technologies for Information Transfer

9-12.PS.2.3.a

9-12.P.1.2.a

9-12.P.1.2.b

Next Generation Science Standards

Matter and Its Interactions

HS-PS1-15

HS-PS2-1

Florida Department of Education

Earth and Space Science

SC.912.E.5

SC.912.E.5.2

SC.912.P.10

SC.912.P.10.10

Texas Essential Knowledge and Skills

PHYS.5

PHYS.5.F

Chemistry and Physics

IPC.5

IPC.5.B

IPC.5.D

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

South Carolina College and Career Ready Science Standards

P-PS2-5

P-PS3-5

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Forces and Interactions

HS-PS2-1.

Georgia Standards of Excellence

SPS8.

Position and Displacement

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Instantaneous Velocity - I

The average velocity during a time interval cannot tell us how fast or in what direction a particle is moving at any given time during the interval. To ...

Instantaneous Velocity - II

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Average Acceleration

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Instantaneous Acceleration

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Kinematic Equations - I

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Kinematic Equations - II

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Kinematic Equations - III

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Kinematic Equations: Problem Solving

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Free-falling Bodies: Introduction

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Free-falling Bodies: Example

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velocity-and-position-by-graphical-method

Velocity and Position by Graphical Method

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Velocity and Position by Integral Method

If acceleration as a function of time is known, then velocity and position functions can be derived using integral calculus. For constant acceleration, ...

Use models (graphs, equations, diagrams) to infer motion in one dimension.

PS.Phy.1.1

Position and Displacement Vectors

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average-and-instantaneous-velocity-vectors

Average and Instantaneous Velocity Vectors

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Acceleration Vectors

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Direction of Acceleration Vectors

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Projectile Motion

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principle-linear-impulse-momentum-for-single-particle-problem

Principle of Linear Impulse and Momentum for a Single Particle: Problem Solving

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Use models (graphs, equations, diagrams) to infer motion in two dimensions.

PS.Phy.1.2

Analyze the motion of objects using time, distance, displacement, speed, velocity, and acceleration.

Contact and Field Forces in Physics

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