What is the Zeroth Law of Thermodynamics?

Summary

This script explains the concept of thermal equilibrium and introduces the zeroth law of thermodynamics, which establishes temperature as a measurable and universal property. It highlights the significance of temperature scales like Fahrenheit, Celsius, and Kelvin, and explores how temperature affects matter's properties. The script also touches on the use of thermometers, thermal imaging, and the potential dangers of thermal shock when objects at different temperatures come into contact.

Takeaways

• 🌡️ Temperature is a fundamental and measurable property of matter that can be determined using thermometers.
• 🔄 The zeroth law of thermodynamics states that if two systems are in thermal equilibrium with a third, they are in thermal equilibrium with each other.
• 📊 The zeroth law allows us to establish temperature as a measurable and universal property, enabling the creation of temperature scales.
• 🌡️ Daniel Gabriel Fahrenheit and Anders Celsius developed early temperature scales, with Celsius being more commonly used today.
• 🔵 The Kelvin scale, used by scientists worldwide, defines 0 as absolute zero, a concept tied to the third law of thermodynamics.
• 💧 Properties of matter change with temperature, such as liquids expanding or contracting and changes in material conductivity.
• 🌡️ Traditional thermometers measure temperature by observing the expansion of liquids like mercury.
• 📱 Modern electronic thermometers use thermistors, where resistance changes with temperature.
• 🔦 Thermal imaging cameras detect infrared radiation emitted by objects, allowing us to see temperature variations.
• 💥 When objects at different temperatures come into contact, they attempt to reach thermal equilibrium, which can cause thermal shock and potentially break objects like glass.
• 📚 The zeroth law, while seemingly simple, is crucial for defining temperature and understanding the effects of the other laws of thermodynamics.

Q & A

What does it mean for three cups to be in thermal equilibrium?

Three cups being in thermal equilibrium means that they all have the same temperature, which can be confirmed using thermometers.

Why is temperature considered a fundamental property of matter?

Temperature is considered a fundamental property of matter because it can be measured and is a key factor in the interactions between heat and energy with matter.

What are the four laws of thermodynamics?

The four laws of thermodynamics describe heat, energy, and their interactions with matter. They include the first, second, and third laws, which are well-known, and the zeroth law, which underpins all the other laws.

Why is the zeroth law of thermodynamics considered so fundamental?

The zeroth law of thermodynamics is fundamental because it allows us to establish temperature as a measurable and universal property of matter, which in turn enables us to quantify the effects of the other three laws.

How does the zeroth law of thermodynamics mathematically define thermal equilibrium?

The zeroth law of thermodynamics mathematically defines thermal equilibrium as if systems A and B are each in thermal equilibrium with a third system C, then A and B are in thermal equilibrium with each other (A=C and B=C imply A=B).

Who established the first temperature scale still in use today?

Daniel Gabriel Fahrenheit established the first temperature scale that is still in use today, albeit in a slightly altered form.

What is the significance of the Celsius temperature scale?

The Celsius scale is significant because it uses the freezing point of water as 0 degrees and the boiling point as 100 degrees, making it a more relatable scale for everyday temperatures.

What is the Kelvin scale and why is it used by scientists?

The Kelvin scale is an absolute temperature scale where 0 Kelvin is defined as absolute zero, the coldest temperature possible. Scientists use it because it provides a scale that starts from the lowest possible temperature.

How does absolute zero relate to the third law of thermodynamics?

Absolute zero is defined by the third law of thermodynamics as the lowest possible temperature where all molecular motion ceases, and it cannot be reached through any physical process.

How do properties of matter change with temperature?

Properties of matter such as volume (expansion or contraction of liquids), conductivity of wires, and radiation of infrared frequency change with temperature.

What are the different methods used to measure temperature?

Temperature can be measured using old-fashioned thermometers that rely on the expansion of liquids like mercury, modern electronic thermometers that use thermistors, and thermal imaging cameras that detect infrared radiation.

What is thermal shock and how can it break glass?

Thermal shock is a phenomenon that occurs when two objects at significantly different temperatures come into contact, causing a rapid and uneven expansion that can generate enough stress to break materials like glass.

Outlines

00:00

🌡️ Thermodynamics and the Zeroth Law

The paragraph discusses the concept of thermal equilibrium and introduces the zeroth law of thermodynamics. It explains that if three cups are in thermal equilibrium, they all have the same temperature, which is a fundamental property of matter. The zeroth law states that if two systems are in thermal equilibrium with a third, they are in equilibrium with each other. This law is foundational for understanding temperature as a measurable property and leads to the establishment of temperature scales such as Fahrenheit, Celsius, and Kelvin. The Kelvin scale is particularly significant as it defines 0 as absolute zero, a concept related to the third law of thermodynamics.

Keywords

💡Thermal Equilibrium

Thermal equilibrium refers to a state where two or more systems in contact with each other have no net heat flow. This means they have reached the same temperature. In the video, the three cups being in thermal equilibrium illustrates the concept effectively. They all show the same temperature when measured, which is foundational for understanding temperature as a measurable property.

💡Temperature

Temperature is a physical quantity that measures the average kinetic energy of the particles in a substance. It is a fundamental property of matter that indicates the degree of hotness or coldness. The video uses the example of measuring the temperature of three cups to show how temperature is a measurable and universal property, essential for understanding thermodynamics.

💡Zeroth Law of Thermodynamics

The zeroth law of thermodynamics is a fundamental principle that establishes temperature as an observable and measurable property. It states that if two systems are each in thermal equilibrium with a third, they are in thermal equilibrium with each other. The video explains that this law is foundational to the other laws of thermodynamics and allows for the establishment of temperature scales.

💡Thermodynamics

Thermodynamics is the study of the relationships between heat and other forms of energy, particularly work and internal energy. The video script discusses the four laws of thermodynamics, which describe heat, energy, and their interactions with matter. Thermodynamics is central to understanding the behavior of matter at various temperatures.

💡Fahrenheit Scale

The Fahrenheit scale is a temperature scale named after its inventor, Daniel Gabriel Fahrenheit. It is defined by two reference points: the temperature of a mixture of ice and water (32°F) and the temperature of boiling water (212°F). The video mentions this scale as one of the first temperature scales established, which is still in use today.

💡Celsius Scale

The Celsius scale is another temperature scale, named after the Swedish astronomer Anders Celsius. It uses the freezing point of water as 0°C and the boiling point as 100°C. The video script uses this scale as an example of a more common temperature scale that is easier to understand because it relates to familiar points of water's phase changes.

💡Kelvin Scale

The Kelvin scale is an absolute temperature scale that starts at absolute zero, the lowest possible temperature where all thermal motion ceases. The video explains that this scale is used by scientists worldwide because it is based on a fundamental physical concept, unlike the arbitrary zero points of the Fahrenheit and Celsius scales.

💡Thermal Expansion

Thermal expansion is the process by which the size of a material changes with temperature. When heated, materials generally expand, and when cooled, they contract. The video mentions this concept in relation to how liquids can expand or contract, which is a principle used in old-fashioned thermometers that rely on the expansion of mercury or other liquids.

💡Thermoresistor

A thermistor is a type of resistor whose resistance changes with temperature. This property is used in modern electronic thermometers to measure temperature. The video script explains that thermistors are a common component in temperature sensing, showcasing the evolution from liquid-based to electronic thermometers.

💡Thermal Imaging

Thermal imaging is a technique that uses infrared radiation to visualize differences in temperature. All objects emit infrared radiation, and hotter objects emit more of it. The video script describes how thermal imaging cameras can detect this radiation, allowing us to see heat patterns, which is useful for various applications, including night vision and detecting temperature anomalies.

💡Thermal Shock

Thermal shock is a phenomenon that occurs when a material is exposed to a sudden change in temperature, causing it to expand or contract rapidly. This can lead to mechanical stress and potentially breakage. The video script uses the example of a glass container breaking due to thermal shock when one side is heated while the other remains cold, illustrating the dramatic effects of rapid temperature changes.

Highlights

Three cups are in thermal equilibrium, showing the same temperature.

Temperature is a fundamental and measurable property of matter.

Thermodynamics is described by four laws that govern heat, energy, and their interactions with matter.

The zeroth law of thermodynamics is fundamental and underpins all other laws.

The zeroth law states that if two systems are in thermal equilibrium with a third, they are in equilibrium with each other.

Temperature can be established as a measurable and universal property due to the zeroth law.

Daniel Gabriel Fahrenheit established one of the first temperature scales still in use today.

The Celsius scale uses the freezing and boiling points of water as reference points.

The Kelvin scale defines 0 as absolute zero, the coldest possible temperature.

Properties of matter change with temperature, such as expansion and contraction of liquids.

Old-fashioned thermometers measure temperature through the expansion of liquids like mercury.

Modern electronic thermometers use thermistors, where resistance changes with temperature.

Thermal imaging cameras detect infrared radiation emitted by objects, allowing temperature visualization.

Objects at different temperatures will try to reach thermal equilibrium when brought into contact.

Thermal shock can occur when objects of different temperatures interact, causing strain and potential breakage.

The zeroth law's significance lies in its ability to define temperature and quantify the effects of the other laws.

Transcripts

These three cups are in thermal equilibrium.

I can measure the temperature in all three mugs here with a thermometer and you can see

they are all come up as being the same temperature.

I could also use three different thermometers and they would still say that the temperature

is the same across all three containers.

That�s because temperature is a fundamental and measurable property of matter.

The framework that describes all of thermodynamics can be summed up in the four laws,

and these describe heat, energy, and their interactions with matter.

While the first, second and third laws of thermodynamics are quite well known, there's

a fourth law that underpins all of the other laws.

It was devised after the three laws of thermodynamics,

but was so fundamental and provided such a basis for the other laws,

that it was termed the zeroth law of thermodynamics.

The zeroth law of thermodynamics is actually an observation

and states that if two thermodynamic systems are in thermal equilibrium with a third system,

they are also in thermal equilibrium with each other.

Or to put it mathematically, if A=C and B=C then A must also = B.

If all of these three glasses are at thermal equilibrium, then we can say that they're

all at the same temperature.

And this is where the significance of the zeroth law lies.

It lets us establish temperature as a measurable and universal property of matter.

If something is measurable, then we can create scales for it and this is exactly what happened

with temperature.

The first temperature scale that, in a slightly altered form,

is still in use today was established by Daniel Gabriel Fahrenheit in 1724.

A more common scale, named after Swedish scientist Anders Celsius,

uses the point of water freezing as the 0 point on the scale,

and the boiling of water as the 100th degree on the scale.

Rather than using a scale where 0 is defined arbitrarily,

what we really want is to use a scale where 0 is the coldest temperature you could ever

get to.

Scientists around the world use the Kelvin scale, where 0 is defined as absolute zero.

Absolute zero is something which is defined by the third law of thermodynamics, but that's

something we'll get to in another video.

It was observed that the properties of matter could change with temperature.

For example, liquids can expand or contract when heated or cooled, and the conductivity

of wires can change as a function of temperature.

Some old fashioned thermometers like this one use the expansion of mercury or other

liquids under heat as a measuring tool.

Modern electronic thermometers commonly use thermoresistors, where the resistance in a

material changes with changes in temperature.

Yet another way of looking at temperature is with a thermal imaging camera.

All objects above absolute zero radiate some sort of infrared frequency radiation

with hotter objects radiating higher amounts of infrared.

This allows us to us thermal imaging to see the world even without any visible light.

If two objects at different temperatures are brought into contact with each other,

they will try to reach thermal equilibrium.

If the two objects are of sufficiently different temperatures, the reaction can be rather violent

due to a phenomenon called thermal shock.

Because the heat gradient makes the glass want to expand, but the other side is cold.

This causes a strain that breaks the glass.

The concept of the zeroth law may seem trivial,

but it lets us define temperature,

and that in turn allows us to quantify the effects of the other three laws.