Name: energy forms and conservation
Uploaded: 2020-09-03T13:38:25.000Z
Duration: 4 min 10 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Physical Science

Energy

3.2.9-12.Q

What is Energy?

A energia é definida como a capacidade de ação. A ação é definida como a distância percorrida por um objeto em resposta a uma força aplicada. Por exemplo, quando um livro é levantado do chão e colocado em cima de uma mesa, a ação é feita contra a força da gravidade.A energia é dividida em dois tipos principais:potenciale cinética. A energia potencial é a energia associada à posição, composição ou condição de um objeto. Também é conhecida como a energia em repouso ou a energia armazenada.Por exemplo o livro que se encontra acima do solo, em cima da mesa possui energia potencial devido à sua altura. Esta energia potencial permanece armazenada no livro desde que seja mantido nessa posição. Diferentes formas de energia potencial incluem a energia potencial gravitacional, energia potencial elétrica, energia potencial química, energia nuclear e energia elástica.A energia potencial gravitacional é a forma mais aparente de energia potencial, e isso depende da posição relativa do objeto sob a influência do campo gravitacional. Por exemplo, o livro que se encontra por cima da mesa tem energia potencial gravitacional armazenada nele. A energia potencial elétrica provém da atração ou da repulsa de cargas elétricas, tal como, a energia armazenada dentro de um condensador num circuito elétrico está na forma de energia potencial elétrica.A energia potencial química é a energia armazenada nas moléculas. Por exemplo, a madeira seca armazena energia potencial química que é libertada e convertida noutras formas de energia quando a madeira queima. A energia nuclear provém do núcleo atômico.e a energia elástica é a energia armazenada num objeto devido à sua configuração, tal como uma fisga esticada. A energia cinética é a energia que está associada com o movimento de um objeto. Por exemplo, quando o livro cai da mesa, a sua energia potencial é convertida em energia cinética devido ao seu movimento.A própria energia cinética também existe em diferentes formas nomeadamente as energias mecânica, elétrica, térmica e radiante. Enquanto a energia mecânica deve-se ao movimento mecânico de um objeto como um carro em movimento, a energia elétrica é constituída por um fluxo de cargas elétricas, como se vê nos relâmpagos. Quando a energia cinética está sob a forma de ondas eletromagnéticas, como a energia da luz do sol, torna-se energia radiante.A energia térmica é a energia cinética associada ao movimento dos átomos e moléculas num objeto. À medida que os átomos e as moléculas num objeto se movem ou vibram rapidamente e colidem mais frequentemente uns com os outros, a temperatura do objeto aumenta. O calor de uma chama acesa é um exemplo de energia térmica.O oposto acontece quando as vibrações ou movimentos destes átomos e moléculas abrandam. Diz-se então que o objeto é frio e tem baixa energia térmica como quando a água congela. Todas estas diferentes formas facilitam o fluxo de energia de um tipo para outro, ou de um objeto para outro, para que o trabalho seja feito.A lei da conservação da energia afirma que a energia não é criada nem destruída ela apenas se transforma passando de um tipo para outro. A energia total do sistema, portanto, permanece conservada. No tiro com arco, por exemplo, uma flecha segurada num arco esticado contém energia potencial elástica.Quando o arco é libertado, esta energia potencial é convertida em energia cinética da flecha e a flecha é impulsionada para atingir o alvo. Mais uma vez, a energia total permanece conservada.

o que é energia?

O universo é composto por matéria em diferentes formas, e todas as formas de matéria contêm energia.  As diferentes formas de energia na Terra têm origem no Sol — a principal fonte de energia. As plantas captam a energia da luz do Sol e, através do processo de fotossíntese, convertem-na em energia química. Esta energia armazenada das plantas pode ser aproveitada de muitas maneiras. Por exemplo, comer produtos vegetais como alimento fornece energia para que o nosso corpo funcione, e queimar madeira ou carvão (plantas fossilizadas) gera calor e eletricidade. Portanto, como todas as mudanças de matéria envolvem mudanças na energia, é vital entender como a energia flui de uma forma para a outra. 

A energia é definida como a capacidade de fazer trabalho. O trabalho é feito quando uma força aplicada a um objeto faz com que o objeto se mova contra uma força oposta. Por exemplo, o trabalho é feito quando uma mesa é empurrada através de uma sala contra a resistência do chão. 

A energia pode ser agrupada em dois tipos principais － energia potencial e energia cinética. A energia potencial é a energia associada à posição relativa, composição, ou condição de um objeto. A energia cinética é a energia associada ao movimento do objeto. Por exemplo, a água retida atrás de uma barragem possui energia potencial devido à sua posição acima do solo. Quando flui para baixo através de geradores, ganha energia cinética, que pode ser posta a trabalhar para gerar eletricidade em uma central hidroelétrica. 

<h4>Energia Potencial </h4>

A energia potencial também é conhecida como energia em repouso ou energia armazenada. Os tipos comuns de energia potencial incluem a energia potencial gravitacional armazenada em uma maçã pendurada em uma árvore,  a energia potencial elétrica armazenada em um objeto devido à atração ou repulsão de cargas elétricas, ou a energia potencial química armazenada nas ligações entre átomos e moléculas. Além disso, a energia nuclear armazenada em um núcleo atómico e a energia elástica armazenada em uma mola esticada devido à sua configuração são tipos de energia potencial.

Normalmente, objetos ou sistemas com elevada energia potencial tendem a ser menos estáveis e, portanto, movem-se em direção a níveis de energia mais baixos para alcançar estabilidade. Por exemplo, o elemento radioativo Urânio-235 (U235) tem um núcleo instável. Para ganhar estabilidade, divide-se em elementos mais pequenos, mas estáveis, e liberta a energia nuclear armazenada. Esta energia libertada pode então ser utilizada para gerar eletricidade em centrais nucleares. 

<h4>Energia Cinética </h4>

A quantidade de energia cinética de um objecto depende da sua massa e velocidade. Considere duas esferas de massas diferentes que rebolam por um plano inclinado à mesma velocidade. A bola mais pesada terá mais energia cinética. Da mesma forma, quando duas bolas da mesma massa descem um plano inclinado a velocidades diferentes, a bola que se move mais depressa tem mais energia cinética. 

Existem também formas diferentes de energia cinética, incluindo energia mecânica, elétrica, radiante, sonora, e térmica. A energia mecânica está associada ao movimento de um objeto. Quanto mais rápido um objecto se mover, mais energia mecânica tem.  Por exemplo, uma bala disparada de uma arma ou água que flui para baixo de uma barragem são exemplos de energia mecânica. A energia elétrica é atribuída ao fluxo de cargas elétricas, conforme observado no caso de relâmpagos durante trovoadas ou nos circuitos e dispositivos elétricos do dia-a-dia. A energia radiante é a forma de energia cinética que viaja como ondas eletromagnéticas e pode ser experienciada na forma de luz e calor. A luz solar é um exemplo de energia radiante.

A energia térmica está associada ao movimento aleatório de átomos e moléculas. Quando os átomos e moléculas de um objeto se movem ou vibram rapidamente, eles têm uma energia cinética (KE) média mais alta, e diz-se que o objeto está “quente”. Quando os átomos e moléculas se movem lentamente, eles têm KE média mais baixa, e o objeto é designado como “frio”. Assim, a energia térmica pode ser observada através das mudanças de temperatura de um objeto. Partindo do princípio que não ocorre qualquer reação química ou mudança de fase (como a fusão ou vaporização), aumentar a quantidade de energia térmica em uma amostra de matéria fará com que a sua temperatura aumente. Da mesma forma, assumindo que não ocorre qualquer reação química ou mudança de fase (como condensação ou solidificação), diminuir a quantidade de energia térmica em uma amostra de matéria fará com que a sua temperatura diminua.

<h4>A Lei da Conservação de Energia </h4>

A energia pode ser convertida de uma forma para outra, mas a energia total presente antes de uma mudança existe sempre em alguma forma mesmo após uma mudança. Esta observação é expressa como a Lei da Conservação de Energia. A Lei da Conservação de Energia afirma que a energia não é nem criada nem destruída, embora possa mudar de forma. Assim, a energia total de um sistema permanece constante. Por exemplo, a energia química (um tipo de energia potencial) é armazenada nas moléculas que compõem a gasolina. Quando a gasolina é queimada dentro dos cilindros do motor de um carro, os produtos gasosos de expansão rápida dessa reação química geram energia mecânica (um tipo de energia cinética) quando movem os pistões do cilindro.

Este texto é adaptado de <a href="https://openstax.org/books/chemistry-2e/pages/5-1-energy-basics">Openstax, Chemistry 2e, Section 5.1: Energy Basics.</a>

O que é Energia?

O universo é composto de matéria em diferentes formas, e todas as formas de matéria contêm energia.  As diferentes formas de energia na Terra se originam de ...

Education

JoVE Core

Chemistry

Química

Introduction: Matter and Measurement

Introdução: Matéria e Medida

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

energy forms and conservation

Energy is a property of matter that appears in many forms. On Earth, most energy starts with the Sun. Plants capture light energy from the Sun and use photosynthesis to turn it into chemical energy. That stored energy can then move through living things and materials in several ways. People get energy from plant foods, and wood or coal, which come from fossilized plants, can be burned to produce heat and electricity.

Energy is defined as the ability to do work. Work happens when a force moves an object against a resisting force. Pushing a table across a room against the floor is one example. To understand changes in matter, it helps to track how energy changes from one form to another.

Energy is often grouped into two main types: potential energy and kinetic energy. Potential energy is stored energy linked to an object’s position, composition, or condition. Kinetic energy is the energy of motion. Water held behind a dam has potential energy because of its height. When it flows downward through generators, it gains kinetic energy and can help produce electricity in a hydroelectric power plant.

Potential energy is sometimes called energy at rest. It includes gravitational potential energy, such as an apple hanging from a tree, electrical potential energy from the attraction or repulsion of charges, and chemical potential energy stored in bonds between atoms and molecules. It also includes nuclear energy in an atomic nucleus and elastic energy in a stretched spring. In general, systems with high potential energy are less stable and tend to move toward lower energy states. Uranium-235 is one example. Its unstable nucleus splits into smaller, more stable elements and releases stored nuclear energy that can be used in nuclear power plants.

The amount of kinetic energy depends on mass and speed. If two balls move at the same speed, the heavier ball has more kinetic energy. If two balls have the same mass, the faster one has more kinetic energy. Kinetic energy includes mechanical, electrical, radiant, sound, and thermal energy. Mechanical energy is tied to motion, like a bullet fired from a gun or water moving down a dam. Electrical energy comes from the flow of electric charges, such as lightning or electricity in circuits. Radiant energy travels as electromagnetic waves and includes sunlight. Thermal energy comes from the random motion of atoms and molecules, so faster motion means higher average kinetic energy and a hotter object. Slower motion means lower average kinetic energy and a colder object. If no chemical reaction or phase change happens, adding thermal energy raises temperature, and removing it lowers temperature.

Energy can change form, but it is not created or destroyed. This is the Law of Conservation of Energy. The total energy in a system stays constant even when energy is converted from one form to another. Gasoline shows this change clearly. It stores chemical energy, which is a type of potential energy. When gasoline burns in a car engine, the reaction produces gases that move the pistons and create mechanical energy, which is a type of kinetic energy.

Energy Forms and Conservation

scientific laws and theories

How Science Explains Laws and Theories

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the scientific method

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physical and chemical properties of matter

physical-and-chemical-properties-of-matter

Distinguishing Physical and Chemical Changes

Matter can be identified by its properties, which are the features that help us tell one substance from another. These properties fall into two main groups: physical properties and chemical properties. Understanding the difference helps explain how matter changes. A physical property is a feature of matter that is not linked to a change in chemical composition. Examples include density, color, hardness, melting point, boiling point, and electrical conductivity. Some physical properties can be...

what is energy?

Energy is a property of matter that appears in many forms. On Earth, most energy starts with the Sun. Plants capture light energy from the Sun and use photosynthesis to turn it into chemical energy. That stored energy can then move through living things and materials in several ways. People get energy from plant foods, and wood or coal, which come from fossilized plants, can be burned to produce heat and electricity. Energy is defined as the ability to do work. Work happens when a force moves...

classifying matter by state

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measurement: standard units

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classifying matter by composition

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measurement: derived units

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uncertainty in measurement: accuracy and precision

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uncertainty-in-measurement-significant-figures

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key terms and concepts

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Energy Forms and Conservation | JoVE K12

chemistry

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3.2.9-12.R

Life Science

matter-and-energy-in-organisms-and-ecosystems

Matter and Energy in Organisms and Ecosystems

3.1.9-12.F

Louisiana Student Standards for Science

High School

HS-PS3-3

HS-PS3-4

Life Sciences

from-molecules-to-organisms-structures-and-processes

From Molecules To Organisms: Structures And Processes

HS-LS1-7

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Ohio’s Learning Standards and Model Curriculum

Study Of Matter

Classification of matter

Tennessee Academic Standards

Physics

PHYS.PS3.2

PHYS.PS3.3

CHEM1.PS3.4

Virginia  Standards of Learning

HIgh School

CH.7

CH.7.a

Arizona Science Standards

Earth and Space Science

HS.E1

HS.E1U1.12

HS.E1U1.13

HS+Phy.P4

HS+Phy.P4U1.6

HS.P4

HS.P4U3.9

Alabama Course of Study Science

9-12.PS.1.1

Matter and Its Interactions

9-12.PS.3.4.h

Earth's Place in the Universe

9-12.ESS.1.1

Next Generation Science Standards

Florida Department of Education

SC.912.E.7

SC.912.E.7.1

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South Carolina College and Career Ready Science Standards

C-PS3-4

P-PS3-1

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3.2.9-12.O

Types of Potential Energy

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3.2.9-12.P

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Force and Potential Energy in One Dimension

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Force and Potential Energy in Three Dimensions

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Energy Diagrams - I

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Energy Diagrams - II

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3.2.9-12.S

Energy Forms and Conservation

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