Name: three ways heat moves between objects
Uploaded: 2023-04-30T12:29:55.000Z
Duration: 1 min 14 s
Channel: JoVE

K12 Standards

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

NC K-12 Science Standard Course of Study

9-12

Physical Science

Energy

PS.PSc.7.1

Mechanisms of Heat Transfer I

Es gibt unzählige Beispiele für Wärmeübertragung, wie z. B. das Verbrennen der Haut durch Halten einer heißen Pfanne, das Kochen von Milch oder das Erhitzen von Lebensmitteln in der Mikrowelle.
Wenn ein Temperaturgradient vorhanden ist, kann die Wärmeübertragung auf drei Arten erfolgen: Leitung, Konvektion und Strahlung.
Leitung ist der Prozess, bei dem Wärme von einem heißen Bereich in einen kalten Bereich innerhalb eines Objekts oder zwischen zwei Objekten in physischem Kontakt übertragen wird.
Wenn zum Beispiel eine Pfanne über einem Feuer aufgestellt wird, überträgt sich die Hitze auf die Pfanne und schließlich wird sie heiß.
Wenn ein Ende eines Stahllöffels über einem Feuer platziert wird, wird das andere Ende aufgrund der Wärmeübertragung heiß.
In der Konduktion haben die Moleküle der heißen Seite eine höhere kinetische Energie. Sie kollidieren mit den Molekülen der kälteren Region und übertragen Energie.
Die Geschwindigkeit der Wärmeübertragung durch Leitung wird durch eine Gleichung angegeben, die den Temperaturgradienten, die Oberfläche und die Dicke des Materials umfasst, durch das die Wärme fließt.
"K" ist die Wärmeleitfähigkeit des Materials, die bei Leitern hoch und bei Isolatoren niedrig ist.

<ol>
	<li>OpenStax. (2019). Universitätsphysik Vol. 2. [Webversion]. Abgerufen von <a href="https://openstax.org/details/books/university-physics-volume-2">https://openstax.org/details/books/university-physics-volume-2</a>; Seiten 35-36</li>
</ol>

mechanismen des wärmeübertrags i

Genau so interessant wie die Auswirkungen des Wärmeübertrags auf ein System sind die Methoden, durch die der Wärmeübertrag stattfindet. Immer wenn es einen Temperaturunterschied gibt, findet Wärmeübertrag statt. Er kann schnell erfolgen, wie zum Beispiel durch eine Pfanne, oder langsam, wie zum Beispiel durch die Wände einer Picknickkühlbox. So viele Prozesse beinhalten Wärmeübertrag, dass es schwer vorstellbar ist, dass keine Wärmeübertragung stattfindet. Dennoch findet jeder Wärmeübertrag nur auf drei Arten statt: durch Leitung, Konvektion und Strahlung.

In einem Kamin zum Beispiel erfolgt die Wärmeübertragung durch alle drei Methoden: Leitung, Konvektion und Strahlung. Strahlung ist für den Großteil der in den Raum übertragenen Wärme verantwortlich. Wärmeübertrag findet auch durch Leitung in den Raum statt, jedoch viel langsamer. Wärmeübertrag durch Konvektion findet ebenfalls statt, indem kalte Luft durch die Fenster in den Raum strömt und heiße Luft den Raum durch den Kamin verlässt.

Leitung ist die Wärmeübertragung durch stationäre Materie durch physischen Kontakt. Die Materie ist nur makroskopisch betrachtet stationär, da thermische Bewegung der Atome und Moleküle bei jeder Temperatur über dem absoluten Nullpunkt stattfindet. Wärme, die von einem Herd über den Boden einer Pfanne auf das Essen in der Pfanne übertragen wird, erfolgt durch Leitung.

Mechanismen des Wärmeübertrags I

Genauso interessant wie die Auswirkungen des Wärmeübergangs auf ein System sind die Methoden, mit denen der Wärmeübergang erfolgt. Wann immer es eine Temperatur gibt ...

Education

Lehre

JoVE Core

Physics

Physik

Unit 1

Einheit 1

Temperature and Heat

Temperatur und Wärme

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

three ways heat moves between objects

Heat transfer happens when there is a temperature difference. It can move fast, like through a cooking pan, or slowly, like through the walls of a picnic ice box. Heat transfer appears in many everyday situations, so it is hard to find a place where it does not occur.

There are only three ways heat is transferred: conduction, convection, and radiation. A fireplace shows all three at once. Radiation carries most of the heat into the room. Conduction also moves heat into the room, but much more slowly. Convection happens when cold air enters around the windows and hot air rises up the chimney.

Conduction is heat transfer through stationary matter by direct contact. The matter may look still on a large scale, but atoms and molecules still move because of thermal motion above absolute zero. A stove burner heating the bottom of a pan is a clear example of conduction, and the heat then moves from the pan to the food.

Three Ways Heat Moves Between Objects

temperature and thermal equilibrium

Heat, Temperature, and Everyday Energy

Heat and temperature are key ideas in thermodynamics and in everyday life. People often connect temperature with hot and cold, but science gives it a more precise meaning. Temperature is the quantity measured with a thermometer. It is also linked to the average translational kinetic energy of particles. Heat is different from temperature. Heat is energy that moves from one place or material to another because there is a difference in temperature. That difference in temperature keeps heat...

zeroth law of thermodynamics

Thermal Equilibrium and the Zeroth Law

The zeroth law of thermodynamics explains thermal equilibrium between objects. If object A is in equilibrium with object B, and object B is in equilibrium with object C, then object A is also in equilibrium with object C. This transitive relationship is the key idea behind the law. A simple example uses metal blocks and a metal plate at room temperature. A cold metal block and a hot metal block are both placed on the plate. Over time, the cold block and the plate reach thermal equilibrium, and...

thermometers and temperature scales

How Thermometers Measure Heat

Thermometers measure temperature by using physical properties that change in a predictable way. One common example is volume. For most substances, volume increases as temperature rises. That idea is used in alcohol thermometers and in the original mercury thermometers. Other thermometer designs use different temperature-sensitive properties. Some measure electrical resistance, color, or the emission of infrared radiation. The alcohol thermometer is a common example. It contains red-dyed...

gas thermometers and the kelvin scale

Kelvin Temperature and Gas Thermometer Standards

Kelvin temperature is the absolute scale used in science, and it starts at absolute zero. That zero point matches the lowest possible temperature, where molecular motion reaches zero or the minimum allowed by quantum mechanics. Scientists use this scale because some physical quantities, such as the volume of an ideal gas, depend directly on absolute temperature. The Kelvin scale is part of the SI system of units, so its definition is more precise than simply using water’s freezing and boiling...

thermal expansion

Thermal Expansion in Air, Water, and Solids

Thermal expansion is the change in size or volume of a material as its temperature changes. A common example is the alcohol inside a thermometer. As the temperature rises, the alcohol expands and shows the change. Heated air also expands. It becomes less dense than the cooler air around it, so the surrounding air pushes it upward. This is why steam and smoke rise and why hot air balloons float. The same effect happens in liquids and gases, and it helps move heat upward in homes, oceans, and...

thermal stress

How Temperature Changes Create Stress

Thermal stress is the stress that builds up when an object changes temperature but cannot expand or contract freely. If the object would expand without restraint, the stress is compressive. If it would contract, the stress is tensile. This stress from heating or cooling can become large enough to cause damage. Engineers often reduce it by designing parts so they can move as temperature changes. Highway blocks, for example, are separated by gaps so thermal stress does not build up. When gaps...

thermal expansion and thermal stress: problem solving

thermal-expansion-and-thermal-stress-problem-solving

Golden Gate Bridge Thermal Expansion

Thermal expansion and thermal stress are shown through the Golden Gate Bridge. The bridge faces temperatures from -15 °C to 40 °C. At its coldest, the main span is 1275 m long. Assuming the bridge is made entirely of steel, the example asks for the change in its length across this temperature range. To solve the problem, the known values must be identified first. The initial length is 1275 m. The coefficient of linear expansion for steel is 12 x 10 -6 /°C, and the change in temperature is 55...

heat flow and specific heat

Heat Units and Specific Heat

Heat is energy transferred because of a temperature difference, and it can change an object’s temperature. Since heat is energy, its SI unit is the joule (J). Heat transfer is the movement of energy from one place or material to another, and it plays a role in home heating, cooking, and many industrial processes. Two common units for heat are the calorie and the kilocalorie. A calorie (cal) is the energy needed to change the temperature of 1 g of water by 1 °C, specifically between 14.5 °C and...

phase changes

Heat and Phase Change Energy

Heat and phase change energy explain why substances melt, freeze, boil, and condense. A solid turns into a liquid during melting, also called fusion. The reverse process is freezing. A liquid turns into a gas during evaporation. The reverse process is condensation. Each substance changes phase at specific temperatures. The melting point is the temperature where a substance melts or freezes. The boiling point is the temperature where a substance boils or condenses. These temperatures depend on...

calorimetry

Heat Exchange in an Insulated System

Calorimetry studies heat exchange in an insulated system. A calorimeter is a container that prevents heat transfer in or out. Scientists use calorimetry to measure heat and specific heat capacity. A calorimetry problem is any situation where the objects are thermally isolated from their surroundings. The key idea comes from conservation of energy. During heat transfer, the heat gained by the colder object must equal the heat lost by the hotter object. A simple example is water poured into a...

mechanisms of heat transfer i

Heat transfer happens when there is a temperature difference. It can move fast, like through a cooking pan, or slowly, like through the walls of a picnic ice box. Heat transfer appears in many everyday situations, so it is hard to find a place where it does not occur. There are only three ways heat is transferred: conduction, convection, and radiation. A fireplace shows all three at once. Radiation carries most of the heat into the room. Conduction also moves heat into the room, but much more...

mechanisms of heat transfer ii

Convection and Radiation in Heat Transfer

Convection and radiation are two major ways heat moves. In convection, thermal energy is carried by the large-scale flow of matter. Warm air and water rise because they are less dense, so ocean currents and large-scale atmospheric circulation move heat from the tropics toward the poles and move cold air from the poles toward the tropics. Earth’s rotation changes these moving air currents. It interacts with the flow and helps produce the eastward movement of air in the temperate zones.

conduction, convection and radiation: problem solving

conduction-convection-and-radiation-problem-solving

Heat Transfer Calculations with Conduction, Convection

Heat transfer calculations with conduction and convection use the temperature difference to find the rate of heat flow. Radiation can also be part of the process. The main idea is that heat moves only because one area is hotter than another, and a larger temperature difference leads to faster transfer. To solve a heat transfer problem, first identify the type of transfer involved. It may be conduction, convection, radiation, or a combination of all three. Next, write down the unknown...

radiation: applications

Earth’s Energy Balance and Greenhouse Effect

Earth’s energy balance and the greenhouse effect help explain its average temperature. Earth is in radiative contact with both the Sun and dark space. It receives almost all of its energy from solar radiation, and it reflects some of that energy back into outer space. Dark space is very cold, about 3 K, so Earth also radiates energy into it. Heat can move quickly from soil and grasses, and frost can form on clear summer evenings, even in warm latitudes. In a first approximation, Earth’s...

absorption of radiation

Radiation Heat Transfer and Thermographs

Radiation heat transfer depends on temperature, surface area, and emissivity. The Stefan-Boltzmann law describes the rate of heat transfer by emitted radiation. In this law, σ is the Stefan-Boltzmann constant, A is the object’s surface area, and T is its temperature in kelvins. The fourth-power dependence on absolute temperature makes radiation highly sensitive to small temperature changes. Even a slight rise in temperature can change the emitted heat a lot. That sensitivity is why radiation...

key terms and concepts

Learn how heat transfers by conduction, convection, and radiation. See how a fireplace and a cooking pan show these three heat-transfer methods.

Three Ways Heat Moves Between Objects | JoVE K12

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Pennsylvania State Academic Standards

Earth and Space Science

Earth's Systems

3.3.9-12.H

Weather and Climate

3.3.9-12.E

Louisiana Student Standards for Science

High School

Earth Science

Earth’s Systems

HS-ESS2-3

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HS-PS3-4

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Ohio’s Learning Standards and Model Curriculum

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PHYS.PS3.2

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ES.12

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4.1.1 9E.4.1.1.2

1.2.1 9C.4.2.1.2

Texas Essential Knowledge and Skills

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112.49.c.8.

112.49.c.8.A.

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New Jersey Student Learning Standards for Science

Earth's Place in the Universe

HS-ESS1-1

Arizona Science Standards

HS+Phy.P4

HS+Phy.P4U2.7

HS.P4

HS.P4U1.8

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9-12.PS.1.1.b

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New York State Science Learning Standards

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HS. ESS2-3.

Georgia Standards of Excellence

SPS7.

Modes of Heat Transfer

Energy Basics

Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter.

Chemical changes and their accompanying ...

Just as interesting as the effects of heat transfer on a system are the methods by which the heat transfer occur. Whenever there is a temperature ...

Mechanisms of Heat Transfer II

In convection, thermal energy is carried by the large-scale flow of matter. Ocean currents and large-scale atmospheric circulation, which result from the ...

Conduction, Convection and Radiation: Problem Solving

There are three methods by which heat transfer can take place: conduction, convection, and radiation. Each method has unique and interesting ...

Use models to explain thermal energy and its transfer.

The universe is composed of matter in different forms, and all forms of matter contain energy.&#160; The different forms of energy on Earth originate from ...

Types of Potential Energy

Potential energy is also known as energy at rest or stored energy. Common types of potential energy include the gravitational potential energy stored in ...

Types of Kinetic Energy

The amount of kinetic energy of an object depends on its mass and speed. Consider two balls of different masses rolling down an inclined plane at the same ...

Conservation of Mechanical Energy

The mechanical energy E of a system is the sum of its potential energy U and the kinetic energy K of the objects within it. What happens to this ...

/files/media/science-education/science-education-thumbs/14702.jpg

Conservative Forces

According to the law of conservation of energy, any transition between kinetic and potential energy conserves the total energy of the system. Hence, the ...

Non-conservative Forces

Non-conservative forces are dissipative forces such as friction or air resistance. These forces take energy away from a system as it progresses. Unlike ...

Conservation of Energy

The terms &#39;conserved quantity&#39;&#160;and &#39;conservation law&#39;&#160;have specific scientific meanings in physics, which differ from the ...

Conservation of Energy: Application

When solving problems using the energy conservation law, the object (system) to be studied should first be identified. Often, in applications of energy ...

Use mathematics and computational thinking to explain the Law of Conservation of Energy in a mechanical system in terms of kinetic and potential energy.

PS.PSc.7.2

Work

Work is done when energy is transferred from one object to another. In other words, work is when a force acts on something that undergoes a displacement ...

Positive, Negative, and Zero Work

Work is done on an object when energy is transferred to the object. In other words, work is done when a force acts on a body that undergoes a displacement ...

Work-energy Theorem

According to Newton&#x2019;s second law of motion, the sum of all the forces acting on a particle (net force) determines the rate of change in the ...

Work and Energy for Variable Forces

When an object is acted upon by a variable force, the amount of work done and the change in energy of the object can be more complex to calculate compared ...

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work-energy-theorem-for-motion-along-a-curve

Work-Energy Theorem for Motion Along a Curve

The work-energy theorem can be generalized to the motion of a particle along any curved path. The simple argument here is that the curved path can be ...

/files/media/science-education/science-education-thumbs/14700.jpg

Work Done Over an Inclined Plane

The center-of-mass framework helps to easily describe the work done on rigid bodies. Since the internal forces in a rigid body do no work, they can be ...

/files/media/science-education/science-education-thumbs/14701.jpg

Work Done by Many Forces

The total work done on an object acted upon by multiple forces can be computed using two methods that give the same result. In one method, the work done ...

/files/media/science-education/science-education-thumbs/14735.jpg

Work Done by Gravity

Gravitation is one of the four fundamental forces in nature. The force between objects on Earth and Earth itself is called gravity.
Like other forces, ...

/files/media/science-education/science-education-thumbs/14750.jpg

Use mathematics and computational thinking to explain work in terms of the relationship among the applied force to an object, the resulting displacement of the object, and the energy transferred to an object.

PS.PSc.7.3

Power

The concept of work involves force and displacement; meanwhile, the work-energy theorem relates the net work done on a body to the difference in its ...

Power Expended by a Constant Force

The relationship between work done and the time taken to do it can be explained using the concept of power. For example, several sprinters in a race may ...

Construct an explanation to infer the relationship between work and power, both quantitatively and qualitatively.

PS.PSc.7.4

Analyze energy transfers and transformations within a mechanical system.

Three Ways Heat Moves Between Objects

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