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608

4 Jul 2025

3 pages

Exploring Density, States of Matter, and How Heat Changes Things

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Los

@los

A comprehensive overview of molecules, matter, and related physics concepts.... Show more

Molecules and Matter Summary
Density
p=m/v
Density is a measure of the compactness of a substance. It relates to the mass of a substance to

Changes of State and Internal Energy

This page delves into the processes of state changes and introduces the concept of internal energy in substances.

Changes of state occur when a substance gains or loses energy through heating or cooling. These physical changes are reversible and include melting, freezing, sublimation, condensation, and vaporization.

Vocabulary: Sublimation is the direct transition from solid to gas without passing through the liquid state.

Internal energy is defined as the total energy stored by particles in a substance, comprising both kinetic and potential energy. It excludes gravitational potential energy and the kinetic energy of the whole substance's motion.

Definition: Internal energy is the sum of the kinetic and potential energies of all particles in a substance.

The page explains how heating affects a system's internal energy and introduces the specific heat capacity equation: ΔE = mcΔθ.

Highlight: The effects of heating on internal energy of substances depend on the mass, specific heat capacity, and energy input.

Molecules and Matter Summary
Density
p=m/v
Density is a measure of the compactness of a substance. It relates to the mass of a substance to

Specific Latent Heat and Kinetic Theory of Matter

This final page explores specific latent heat and introduces the kinetic theory of matter, providing deeper insights into the behavior of particles in different states.

Specific latent heat is the energy required to change 1 kg of a substance from one state to another without changing its temperature. It's calculated using the equation E = mL.

Definition: Specific latent heat of fusion refers to the energy needed for solid-liquid state changes, while specific latent heat of vaporization applies to liquid-gas transitions.

The kinetic theory of matter posits that all matter consists of particles in constant motion. As temperature increases, particle motion accelerates.

Example: Einstein linked the Brownian motion of pollen grains to the idea of molecules in perpetual motion.

The theory makes several assumptions about particle behavior, including elastic collisions, random motion, and adherence to Newton's laws of motion.

Highlight: The kinetic theory provides a framework for understanding density in physics concepts and the differences between states of matter in science at a molecular level.

Molecules and Matter Summary
Density
p=m/v
Density is a measure of the compactness of a substance. It relates to the mass of a substance to

Density and States of Matter

This page introduces fundamental concepts in understanding density in physics concepts and the characteristics of different states of matter.

Density is defined as the mass of a substance per unit volume, calculated using the equation ρ = m/V. It measures how compact a substance is, with denser materials having more tightly packed particles.

Definition: Density ρρ is the mass mm of a substance divided by its volume VV, typically measured in kg/m³ or g/cm³.

The three states of matter - solid, liquid, and gas - are explained in detail, focusing on their particle arrangement and behavior.

Example: Water exists in all three states: ice solidsolid, liquid water, and water vapor gasgas.

Solids have strong interparticle forces, fixed lattice arrangements, and high density. Liquids have weaker forces, allowing particles to move past each other while remaining close. Gases have very weak forces, enabling particles to move freely at high speeds with low density.

Highlight: The arrangement and energy of particles determine the state of matter, while the particles themselves remain unchanged across states.



We thought you’d never ask...

What is the Knowunity AI companion?

Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.

Where can I download the Knowunity app?

You can download the app from Google Play Store and Apple App Store.

Is Knowunity really free of charge?

That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.

Can't find what you're looking for? Explore other subjects.

Students love us — and so will you.

4.9/5

App Store

4.8/5

Google Play

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

Best app on earth! no words because it’s too good

Thomas R

iOS user

Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.

Basil

Android user

This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.

Rohan U

Android user

I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.

Xander S

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now

Paul T

iOS user

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

Best app on earth! no words because it’s too good

Thomas R

iOS user

Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.

Basil

Android user

This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.

Rohan U

Android user

I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.

Xander S

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now

Paul T

iOS user

 

Physics

608

4 Jul 2025

3 pages

Exploring Density, States of Matter, and How Heat Changes Things

user profile picture

Los

@los

A comprehensive overview of molecules, matter, and related physics concepts. This guide covers density, states of matter, changes of state, internal energy, specific latent heat, and kinetic theory, providing essential knowledge for understanding differences between states of matter in science... Show more

Molecules and Matter Summary
Density
p=m/v
Density is a measure of the compactness of a substance. It relates to the mass of a substance to

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Changes of State and Internal Energy

This page delves into the processes of state changes and introduces the concept of internal energy in substances.

Changes of state occur when a substance gains or loses energy through heating or cooling. These physical changes are reversible and include melting, freezing, sublimation, condensation, and vaporization.

Vocabulary: Sublimation is the direct transition from solid to gas without passing through the liquid state.

Internal energy is defined as the total energy stored by particles in a substance, comprising both kinetic and potential energy. It excludes gravitational potential energy and the kinetic energy of the whole substance's motion.

Definition: Internal energy is the sum of the kinetic and potential energies of all particles in a substance.

The page explains how heating affects a system's internal energy and introduces the specific heat capacity equation: ΔE = mcΔθ.

Highlight: The effects of heating on internal energy of substances depend on the mass, specific heat capacity, and energy input.

Molecules and Matter Summary
Density
p=m/v
Density is a measure of the compactness of a substance. It relates to the mass of a substance to

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Specific Latent Heat and Kinetic Theory of Matter

This final page explores specific latent heat and introduces the kinetic theory of matter, providing deeper insights into the behavior of particles in different states.

Specific latent heat is the energy required to change 1 kg of a substance from one state to another without changing its temperature. It's calculated using the equation E = mL.

Definition: Specific latent heat of fusion refers to the energy needed for solid-liquid state changes, while specific latent heat of vaporization applies to liquid-gas transitions.

The kinetic theory of matter posits that all matter consists of particles in constant motion. As temperature increases, particle motion accelerates.

Example: Einstein linked the Brownian motion of pollen grains to the idea of molecules in perpetual motion.

The theory makes several assumptions about particle behavior, including elastic collisions, random motion, and adherence to Newton's laws of motion.

Highlight: The kinetic theory provides a framework for understanding density in physics concepts and the differences between states of matter in science at a molecular level.

Molecules and Matter Summary
Density
p=m/v
Density is a measure of the compactness of a substance. It relates to the mass of a substance to

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Density and States of Matter

This page introduces fundamental concepts in understanding density in physics concepts and the characteristics of different states of matter.

Density is defined as the mass of a substance per unit volume, calculated using the equation ρ = m/V. It measures how compact a substance is, with denser materials having more tightly packed particles.

Definition: Density ρρ is the mass mm of a substance divided by its volume VV, typically measured in kg/m³ or g/cm³.

The three states of matter - solid, liquid, and gas - are explained in detail, focusing on their particle arrangement and behavior.

Example: Water exists in all three states: ice solidsolid, liquid water, and water vapor gasgas.

Solids have strong interparticle forces, fixed lattice arrangements, and high density. Liquids have weaker forces, allowing particles to move past each other while remaining close. Gases have very weak forces, enabling particles to move freely at high speeds with low density.

Highlight: The arrangement and energy of particles determine the state of matter, while the particles themselves remain unchanged across states.

We thought you’d never ask...

What is the Knowunity AI companion?

Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.

Where can I download the Knowunity app?

You can download the app from Google Play Store and Apple App Store.

Is Knowunity really free of charge?

That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.

Can't find what you're looking for? Explore other subjects.

Students love us — and so will you.

4.9/5

App Store

4.8/5

Google Play

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

Best app on earth! no words because it’s too good

Thomas R

iOS user

Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.

Basil

Android user

This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.

Rohan U

Android user

I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.

Xander S

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now

Paul T

iOS user

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

Best app on earth! no words because it’s too good

Thomas R

iOS user

Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.

Basil

Android user

This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.

Rohan U

Android user

I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.

Xander S

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now

Paul T

iOS user