Subjects
Maths
Chemistry
Biology
English Language
History
Responding to change (a2 only)
Infection and response
Homeostasis and response
Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
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Britain & the wider world: 1745 -1901
1l the quest for political stability: germany, 1871-1991
The cold war
Inter-war germany
Medieval period: 1066 -1509
2d religious conflict and the church in england, c1529-c1570
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
2m wars and welfare: britain in transition, 1906-1957
World war two & the holocaust
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
World war one
Britain: 1509 -1745
Show all topics
Physics
11 Dec 2025
186
7 pages
Charlotte @charlotte26
Ever wondered why ice floats on water or why you can smell food cooking from across the room?... Show more
The particle model explains everything around you through three simple states. Solids have particles packed in regular arrangements that just vibrate around fixed points - think of them as people standing in neat rows, barely moving. This gives solids their fixed shape, volume, and high density.
Liquids are where things get interesting. The particles stay closely packed but can now slide past each other like people in a crowded corridor. They keep similar density to solids but lose that fixed shape.
Gases are the rebels of the particle world. Their particles zoom around randomly with loads of space between them, making gases much less dense than solids or liquids.
Top Tip Remember that density decreases as you go from solid to liquid to gas because the particles get more spread out!
When matter changes state, you're witnessing a physical change - no new substances form, and mass stays constant throughout. The particle model shows us six key transitions melting, freezing, evaporation, condensation, sublimation, and deposition.
Specific heat capacity measures how much energy you need to heat up 1kg of a substance by 1°C. Different materials need different amounts of energy - that's why metal feels colder than wood at the same temperature.
The essential equation is change in thermal energy = mass × specific heat capacity × temperature change. This formula helps you calculate exactly how much energy any heating or cooling process requires.
Exam Smart Always include units in your calculations - energy in Joules (J), mass in kilograms (kg), and temperature in degrees Celsius (°C).
This practical investigation lets you measure specific heat capacity yourself using some clever physics. You'll need to measure the mass of your material sample, then wrap it in insulation to prevent heat escaping to the surroundings.
The method involves heating the block with a known voltage whilst recording temperature and current every ten minutes. The electrical heater does work on the block, transferring energy to its thermal store.
Your stopwatch timing needs to be spot-on because you're measuring how energy input relates to temperature rise. The insulation is crucial - without it, loads of heat escapes and ruins your results.
Safety Note Always handle heated materials carefully and ensure electrical equipment is checked before use - hot blocks can cause burns!
Specific latent heat is the energy needed to change 1kg of a substance's state without changing its temperature. This might sound odd, but energy still goes in even when the thermometer reading stays the same.
There are two types you need to know latent heat of fusion and latent heat of vaporisation . The substance must already be at the right temperature before the state change begins.
The equation is thermal energy for state change = mass × specific latent heat. The key difference from specific heat capacity is that latent heat involves no temperature change - all the energy goes into breaking or forming bonds between particles.
Remember During state changes, temperature stays constant even though energy is still being transferred - this often catches students out in exams!
Internal energy combines all the kinetic energy (particle movement and vibration) and potential energy (forces between particles) in a system. When you heat something, particles gain kinetic energy and move faster, potentially causing temperature rises or state changes.
Pressure results from gas particles colliding with container walls, creating force per unit area. Want higher pressure? Increase the temperature - this gives particles more kinetic energy, making them move faster and collide more frequently with greater force.
Understanding internal energy helps explain why heating doesn't always increase temperature. During state changes, the extra energy breaks bonds rather than speeding up particles.
Think About It A pressure cooker works by increasing pressure to raise the boiling point - food cooks faster at higher temperatures!
Density equals mass per unit volume, and measuring it depends on whether your sample is a regular solid, irregular solid, or liquid. Each method uses the same principle but different techniques to find volume.
For regular solids, calculate volume using length × width × height measurements. Irregular solids require the displacement method - measure how much water they push aside in a displacement can or measuring cylinder.
Liquids need a measuring cylinder approach weigh the empty cylinder, add your liquid to measure volume, then weigh again. The difference gives you the liquid's mass, and you already know the volume.
Practical Tip Always read measuring cylinders at eye level from the bottom of the meniscus for accurate volume readings!
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.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp Store
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
Charlotte
@charlotte26
Ever wondered why ice floats on water or why you can smell food cooking from across the room? It's all down to the particle model of matter- a brilliant way to explain how tiny particles behave differently in solids,... Show more
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The particle model explains everything around you through three simple states. Solids have particles packed in regular arrangements that just vibrate around fixed points - think of them as people standing in neat rows, barely moving. This gives solids their fixed shape, volume, and high density.
Liquids are where things get interesting. The particles stay closely packed but can now slide past each other like people in a crowded corridor. They keep similar density to solids but lose that fixed shape.
Gases are the rebels of the particle world. Their particles zoom around randomly with loads of space between them, making gases much less dense than solids or liquids.
Top Tip: Remember that density decreases as you go from solid to liquid to gas because the particles get more spread out!
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By signing up you accept Terms of Service and Privacy Policy
When matter changes state, you're witnessing a physical change - no new substances form, and mass stays constant throughout. The particle model shows us six key transitions: melting, freezing, evaporation, condensation, sublimation, and deposition.
Specific heat capacity measures how much energy you need to heat up 1kg of a substance by 1°C. Different materials need different amounts of energy - that's why metal feels colder than wood at the same temperature.
The essential equation is: change in thermal energy = mass × specific heat capacity × temperature change. This formula helps you calculate exactly how much energy any heating or cooling process requires.
Exam Smart: Always include units in your calculations - energy in Joules (J), mass in kilograms (kg), and temperature in degrees Celsius (°C).
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
This practical investigation lets you measure specific heat capacity yourself using some clever physics. You'll need to measure the mass of your material sample, then wrap it in insulation to prevent heat escaping to the surroundings.
The method involves heating the block with a known voltage whilst recording temperature and current every ten minutes. The electrical heater does work on the block, transferring energy to its thermal store.
Your stopwatch timing needs to be spot-on because you're measuring how energy input relates to temperature rise. The insulation is crucial - without it, loads of heat escapes and ruins your results.
Safety Note: Always handle heated materials carefully and ensure electrical equipment is checked before use - hot blocks can cause burns!
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 is the energy needed to change 1kg of a substance's state without changing its temperature. This might sound odd, but energy still goes in even when the thermometer reading stays the same.
There are two types you need to know: latent heat of fusion and latent heat of vaporisation . The substance must already be at the right temperature before the state change begins.
The equation is: thermal energy for state change = mass × specific latent heat. The key difference from specific heat capacity is that latent heat involves no temperature change - all the energy goes into breaking or forming bonds between particles.
Remember: During state changes, temperature stays constant even though energy is still being transferred - this often catches students out in exams!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Internal energy combines all the kinetic energy (particle movement and vibration) and potential energy (forces between particles) in a system. When you heat something, particles gain kinetic energy and move faster, potentially causing temperature rises or state changes.
Pressure results from gas particles colliding with container walls, creating force per unit area. Want higher pressure? Increase the temperature - this gives particles more kinetic energy, making them move faster and collide more frequently with greater force.
Understanding internal energy helps explain why heating doesn't always increase temperature. During state changes, the extra energy breaks bonds rather than speeding up particles.
Think About It: A pressure cooker works by increasing pressure to raise the boiling point - food cooks faster at higher temperatures!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Density equals mass per unit volume, and measuring it depends on whether your sample is a regular solid, irregular solid, or liquid. Each method uses the same principle but different techniques to find volume.
For regular solids, calculate volume using length × width × height measurements. Irregular solids require the displacement method - measure how much water they push aside in a displacement can or measuring cylinder.
Liquids need a measuring cylinder approach: weigh the empty cylinder, add your liquid to measure volume, then weigh again. The difference gives you the liquid's mass, and you already know the volume.
Practical Tip: Always read measuring cylinders at eye level from the bottom of the meniscus for accurate volume readings!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
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.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
5
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp Store
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
Sociology