Name: heat units and specific heat
Uploaded: 2023-04-30T12:29:39.000Z
Duration: 1 min 12 s
Channel: JoVE

K12 Standards

Tennessee Academic Standards

High School

Physics

Energy

PHYS.PS3.2

Heat Flow and Specific Heat

뜨거운 커피 한 잔을 방에 놓으면 대기와 열 평형을 이루기 때문에 온도가 낮아집니다.
온도 구배로 인해 커피에서 전달되는 에너지를 열이라고 하고, 그 과정에서 발생하는 에너지 전달을 열 흐름이라고 합니다.
열의 SI 단위는 줄입니다. 열의 또 다른 표준 단위는 칼로리이며, 여기서 1칼로리는 4.186줄입니다.
또한, 특정 물질의 질량 m의 온도를 T1에서 T2로 올리는 데 필요한 열량은 질량과 온도 변화에 비례합니다. 비례 상수 c를 비열이라고 합니다.
따라서 비열은 물질의 단위 질량 온도를 섭씨 1도 올리는 데 필요한 열량입니다.
물질의 몰당 질량인 몰 질량이 비열에 대한 공식에 사용되는 경우 이를 몰 열 용량이라고 하며 대문자 C로 표시합니다.

<ol>
	<li>오픈스택스. (2019). 대학 물리학 Vol. 2. [웹 버전]. 원본 주소 <a href="https://openstax.org/details/books/university-physics-volume-2">https://openstax.org/details/books/university-physics-volume-2</a>; 19–20쪽.</li>
</ol>

열 흐름과 비열

열은 온도 차이로 인해 발생하는 일종의 에너지 전달로, 물체의 온도를 변화시킬 수 있습니다. 열은 에너지의 한 형태이므로 SI 단위는 줄(J)입니다. 열에 자주 사용되는 또 다른 일반적인 에너지 단위는 칼로리(cal)입니다. 이는 물 1g의 온도를 1°C, 구체적으로 14.5°C와 15.5°C 사이에서 변화시키는 데 필요한 에너지로 정의됩니다. °C, 필요한 에너지는 약간의 온도 의존성을 보이기 때문입니다. 일반적으로 사용되는 또 다른 단위는 킬로칼로리(kcal)로, 물 1kg의 온도를 1℃ 변화시키는 데 필요한 에너지입니다. 질량은 킬로그램 단위로 지정되는 경우가 많기 때문에 킬로칼로리가 더 편리합니다. 혼란스럽게도 음식 칼로리는 실제로 킬로칼로리이며, 이는 포장 라벨에서 쉽게 확인할 수 없는 사실입니다.

열 전달은 온도 차이로 인해 한 장소나 물질에서 다른 장소나 물질로 에너지가 이동하는 것입니다. 열 전달은 가정 난방, 요리 등 일상 활동은 물론 다양한 산업 공정의 기본입니다.

비열은 재료와 그 상에 따라 다릅니다. 예를 들어, 물의 비열은 유리의 5배, 철의 10배입니다. 즉, 물의 온도를 높이려면 유리에 비해 5배, 철에 비해 10배의 열이 필요합니다. 실제로 물은 어떤 물질보다 비열이 가장 큰 것 중 하나이며, 이는 지구상의 생명체를 유지하는 데 중요합니다. 비열 값은 정확하게 계산할 수 있는 간단한 방법이 없기 때문에 일반적으로 측정해야 합니다.

열은 온도 차이로 인해 발생하는 일종의 에너지 전달이며 물체의 온도를 변화시킬 수 있습니다. 열은 한 형태이기 때문에 ...

Education

교육

JoVE Core

물리학

Unit 1

제1단원

Temperature and Heat

온도와 열

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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 15.5 °C because the value changes slightly with temperature. A kilocalorie (kcal) is the energy needed to change the temperature of 1 kg of water by 1 °C. Kilocalories are often more convenient because mass is usually given in kilograms. Food calories are actually kilocalories, even though labels do not always make that clear.

Specific heat depends on the material and its phase. It tells how much heat is needed to raise a substance’s temperature. Water has a specific heat about 5 times that of glass and 10 times that of iron. That means water needs much more heat to warm up by the same amount, and it has one of the largest specific heats of any material. This high value is important for life on Earth.

Specific heat usually must be measured. There is no simple way to calculate it exactly. Understanding heat flow and specific heat helps explain why different materials warm up and cool down at different rates.

Heat Units and Specific Heat

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 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

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...

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 is measured in joules, calories, and kilocalories, and why specific heat makes water warm up more slowly than glass or iron.

Heat Units and Specific Heat | 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.

PHYS.PS3.5

Chemistry

CHEM1.PS3.1

Virginia  Standards of Learning

HIgh School

Physical Science

PS.5

PS.5.b

Minnesota Academic Standards in Science

9-12

1.2.1 9C.4.2.1.2

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

HS-PS3-4

Arizona Science Standards

HS+Phy.P4

HS+Phy.P4U2.7

HS.P4

HS.P4U1.8

HS+Phy.P4U1.6

Texas Essential Knowledge and Skills

CHEM.13

CHEM.13.D

Alabama Course of Study Science

9-12.PS.1.1.c

Earth and Space Science

Earth's Systems

9-12.ESS.2.7

9-12.ESS.2.7.b

Georgia Standards of Excellence

SPS7.

Specific Heat

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Types of Kinetic Energy

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Kinetic Energy - I

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Kinetic Energy - II

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Gravitational Potential Energy

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Elastic Potential Energy

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Conservation of Energy: Application

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Mechanisms of Heat Transfer I

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

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Identify and calculate different types of energy and their transformations (thermal, kinetic, potential, including magnetic and electrical potential energies) from one form to another in a system. Identify and calculate different types of energy and their transformations (thermal, kinetic, potential, including magnetic and electrical potential energies) from one form to another in a system. EXPLANATION:  In 6.PS3 students were introduced to the various types of energy and mechanisms for their transformations. Students should now be able to quantify the total energy of a system as well as quantify each different type of energy in a system. Energy is an abstract concept that does not have a physical form. It is a substance-like quantity that is recognized to be conserved as a system changes. Calculations present an opportunity to observe that potential energies are due to the positions of objects within a field, while kinetic energy is based on an object’s mass and motion. Students can evaluate the total energy of a system by imagining that there are different types of energy storage accounts, just as money can be stored in different accounts. Energy can transferred into or out of any of these accounts. Three different processes can account for all energy changes: working, heating, and radiating. In energy storage due to field effects, such as gravitational or electrostatic fields, the field itself stores the potential energy and not the object in the field.

PHYS.PS3.1

What is Energy?

The universe is composed of matter in different forms, and all forms of matter contain energy. &#xA0;The different forms of energy on Earth originate from ...

Heat is a type of energy transfer that is caused by a temperature difference, and it can change the temperature of an object. Since heat is a form of ...

Investigate conduction, convection, and radiation as a mechanism for the transfer of thermal energy.Investigate conduction, convection, and radiation as a mechanism for the transfer of thermal energy. EXPLANATION: Thermal energy is the energy of a system due to the motion of the particles in that system. One object can transfer its thermal energy to another object through the processes of heating or radiating. Convection and conduction are processes which require a physical medium to transfer the thermal energy. In the case of conduction, two objects are in direct contact, while convection transfers thermal energy through a liquid or gaseous medium. Radiation is a unique form of energy transfer which can transfer without a medium. One packet of this energy is called a photon. The energy of the photon determines the effect that it will have when it interacts with matter. Low energy photons such a microwaves add to the motion of matter and result in an increase of the thermal energy. Photons carry energy from the sun to Earth.

Quantifying Heat

Thermal Energy&#160;

Microscopically, thermal energy is the kinetic energy associated with the random motion of atoms and molecules. Temperature is a ...

Free-falling Bodies: Introduction

All objects, neglecting air resistance, fall with the same acceleration towards the Earth&#39;s center due to the force exerted by the Earth&#39;s ...

Free-falling Bodies: Example

An object falling without any air resistance under the influence of gravitational force is said to be in free-fall. For free-falling bodies, the ...

force-and-potential-energy-in-one-dimension

Force and Potential Energy in One Dimension

Force can be calculated from the expression for potential energy, which is a function of position. The component of a conservative force, in a particular ...

force-and-potential-energy-in-three-dimensions

Force and Potential Energy in Three Dimensions

Consider a particle moving under the action of a conservative force that has components along each coordinate axis. Each component of force is a function ...

Energy Diagrams - I

The dynamics of a mechanical system can be easily understood by interpreting a potential energy diagram. Since energy is a scalar quantity, the ...

Energy Diagrams - II

Energy diagrams are important to understand the dynamics of a system. The topology of an energy diagram helps illustrate the equilibrium points of the ...

Use the principle of energy conservation and mathematical representations to quantify the change in energy of one component of a system when the energy that flows in and out of the system and the change in energy of the other components is known.         Use the principle of energy conservation and mathematical representations to quantify the change in energy of one component of a system when the energy that flows in and out of the system and the change in energy of the other components is known.         EXPLANATION:  In PHYS.PS3.1 students quantify the various types of energy and consider methods for energy transfer. If a student is able to evaluate the total energy of a system, such evaluations before and after a change to a system provide a mechanism to show that energy of a system has been conserved. For example, students might use pie charts to show the distribution of the total energy. For an object about to freefall, the pie chart might be 100% gravitational potential energy. Mid-descent, the energy might be half gravitational potential energy and half kinetic energy. After colliding with the ground, the total energy may have decreased, which can be represented as heat energy lost from the pie chart.

PHYS.PS3.3

Linear Momentum

The term momentum is used in various ways in everyday language, most of which are consistent with the precise scientific definition. Generally, momentum ...

Force and Momentum

Force and momentum are intimately related. Force acting over time can change momentum, and Newton&#39;s second law of motion can be stated in its most ...

Impulse

According to Newton&#8217;s second law of motion, the rate of change of the momentum of an object is the net external force acting on it. The total change ...

Impulse-Momentum Theorem

The total change in the motion of an object is proportional to the total force vector acting on it and the time over which it acts. This product is called ...

Conservation of Momentum: Introduction

The total momentum of a system consisting of N interacting objects is constant in time or is conserved. A system must meet two requirements for its ...

Conservation of Momentum: Problem Solving

Solving problems using the conservation of momentum requires four basic steps:

	Identify a closed system, where the total mass is constant, and no net ...

Types Of Collisions - I

When two objects come in direct contact with each other, it is called a collision. During a collision, two or more objects exert forces on each other in a ...

Types of Collisions - II

When two or more objects collide with each other, they can stick together to form one single composite object (after collision). The total mass of the ...

Elastic Collisions: Introduction

An elastic collision is one that conserves both internal kinetic energy and momentum. Internal kinetic energy is the sum of the kinetic energies of the ...

Elastic Collisions: Case Study

Elastic collision of a system demands conservation of both momentum and kinetic energy. To solve problems involving one-dimensional elastic collisions ...

collisions-in-multiple-dimensions-introduction

Collisions in Multiple Dimensions: Introduction

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Collisions in Multiple Dimensions: Problem Solving

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Assess the validity of the law of conservation of linear momentum (p=mV) by planning and constructing a controlled scientific investigation involving two objects moving in one dimension. Assess the validity of the law of conservation of linear momentum (p=mV) by planning and constructing a controlled scientific investigation involving two objects moving in one dimension. EXPLANATION: Momentum is a useful tool when considering conservation of energy when two objects interact. Attempts to quantify all energy transformation in such a system often fail to account for energies lost due to the production of sound and heat. Collisions where energy is dissipated from the system are known as inelastic collisions. Though system energy may be lost to the surroundings, the conservation of momentum will still be observed. Thus the conservation of momentum can provide a tool to evaluate inelastic collisions.

PHYS.PS3.4

Temperature and Thermal Equilibrium

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The heat capacity of a gas is the amount of heat energy required to raise the temperature of a unit mass of gas by one degree Celsius. It is an important ...

Construct an argument based on qualitative and quantitative evidence that relates the change in temperature of a substance to its mass and heat energy added or removed from a system. Construct an argument based on qualitative and quantitative evidence that relates the change in temperature of a substance to its mass and heat energy added or removed from a system.  EXPLANATION: Two different materials will undergo different degrees of temperature change even with the same amount of energy added to each. Heat capacity is a ratio (the slope of a temperature vs. heat added) that describes the change in temperature of a sample dependent on the amount of heating. Empirical determination of the heat capacity of a substance requires that both phase and mass of the substance are constants. Students can utilize proportional reasoning in the design of a second portion of this experiment to determine the effect of mass on temperature change.

Work-energy Theorem

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Work and Energy for Variable Forces

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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 ...

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Define power and solve problems involving the rate of energy production or consumption (P=∆E/∆t). Explain and predict changes in power consumption based on changes in energy demand or elapsed time. Investigate power consumption and power production systems in common use.  Define power and solve problems involving the rate of energy production or consumption (P=∆E/∆t). Explain and predict changes in power consumption based on changes in energy demand or elapsed time. Investigate power consumption and power production systems in common use. EXPLANATION:  This standard pairs well with PHYS.PS3.6. Students should understand that a given task will require a certain minimum amount of energy. In accordance with the work-energy theorem, this would be described as work done on the system. Power incorporates a rate element into this discussion. An object can be lifted to an identical height by two different mechanisms. The total energy input into the system (the object and Earth’s gravitational field) will be the same in either case. However, if one mechanism for lifting the object does this in a smaller amount of time, it is said to be more powerful. Students may compare two different devices that accomplish the same task, but have different power ratings and explain the impact of the different power ratings on how the devices are used. For example, two microwaves might both pop a bag of popcorn, but a more powerful microwave might do it faster or be more likely to burn the popcorn at recommended time settings.

PHYS.PS3.6

Heat Units and Specific Heat

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