Energy is everywhere around us - from the food we... Show more
SociologySign 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
1
0
issy
16/12/2025
Physics
p1 - knowledge organiser
86
•
16 Dec 2025
•
Energy Topic Knowledge Organizer: Key Information
issy
@issy.studies
Energy Conservation and Efficiency
The most important rule in physics is that energy cannot be created or destroyed - it can only be transferred from one form to another. This is called the law of conservation of energy, and it explains why perpetual motion machines are impossible.
When energy moves through systems, some always gets dissipated (lost to the surroundings). Think about a printer - it receives electrical energy from the power station and converts it to kinetic energy in its moving parts. However, some energy is wasted as thermal energy through heating, which is why printers get warm.
You can reduce unwanted energy transfers in clever ways. Hot water tanks need proper insulation to prevent thermal energy loss. Car engines use lubrication to reduce friction between moving parts, stopping energy being wasted as heat.
Efficiency tells us how good a system is at converting input energy to useful output energy. The formula is: efficiency = useful output energy ÷ total input energy. More aerodynamic lorries are more efficient because they waste less energy fighting air resistance.
Key Point: In any closed system, the total amount of energy always stays the same - it just changes form!
Energy Stores and Calculations
A system is simply an object or group of objects that we're studying. Energy constantly changes between different stores within systems, and you need to spot these changes.
When a football is kicked upwards, its kinetic energy decreases as its gravitational potential energy increases. A squash ball hitting a wall converts kinetic energy into elastic potential energy. Cars accelerating turn chemical energy from fuel into kinetic energy.
The maths behind energy stores is straightforward once you know the formulas:
- Kinetic energy = ½ × mass × speed² (measured in joules)
- Elastic potential energy = ½ × spring constant × extension²
- Gravitational potential energy = mass × gravitational field strength × height
Specific heat capacity is the energy needed to heat 1kg of material by 1°C. The thermal energy equation is: change in thermal energy = mass × temperature change × specific heat capacity.
Power measures the rate of energy transfer - how quickly energy moves. Power = energy transferred ÷ time, measured in watts. An 8W LED bulb uses far less energy per second than a 28W halogen bulb whilst producing similar brightness.
Remember: These energy calculations appear frequently in exams, so practice substituting values into the formulas!
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.
Most popular content: Elastic Potential Energy
Most popular content in Physics
Most popular content
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
Energy Topic Knowledge Organizer: Key Information
issy
@issy.studies
Energy is everywhere around us - from the food we eat to the electricity powering your phone right now. Understanding how energy works, transforms, and moves through systems is crucial for physics and explains everything from why your laptop gets... Show more
Energy Conservation and Efficiency
The most important rule in physics is that energy cannot be created or destroyed - it can only be transferred from one form to another. This is called the law of conservation of energy, and it explains why perpetual motion machines are impossible.
When energy moves through systems, some always gets dissipated (lost to the surroundings). Think about a printer - it receives electrical energy from the power station and converts it to kinetic energy in its moving parts. However, some energy is wasted as thermal energy through heating, which is why printers get warm.
You can reduce unwanted energy transfers in clever ways. Hot water tanks need proper insulation to prevent thermal energy loss. Car engines use lubrication to reduce friction between moving parts, stopping energy being wasted as heat.
Efficiency tells us how good a system is at converting input energy to useful output energy. The formula is: efficiency = useful output energy ÷ total input energy. More aerodynamic lorries are more efficient because they waste less energy fighting air resistance.
Key Point: In any closed system, the total amount of energy always stays the same - it just changes form!
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
Energy Stores and Calculations
A system is simply an object or group of objects that we're studying. Energy constantly changes between different stores within systems, and you need to spot these changes.
When a football is kicked upwards, its kinetic energy decreases as its gravitational potential energy increases. A squash ball hitting a wall converts kinetic energy into elastic potential energy. Cars accelerating turn chemical energy from fuel into kinetic energy.
The maths behind energy stores is straightforward once you know the formulas:
- Kinetic energy = ½ × mass × speed² (measured in joules)
- Elastic potential energy = ½ × spring constant × extension²
- Gravitational potential energy = mass × gravitational field strength × height
Specific heat capacity is the energy needed to heat 1kg of material by 1°C. The thermal energy equation is: change in thermal energy = mass × temperature change × specific heat capacity.
Power measures the rate of energy transfer - how quickly energy moves. Power = energy transferred ÷ time, measured in watts. An 8W LED bulb uses far less energy per second than a 28W halogen bulb whilst producing similar brightness.
Remember: These energy calculations appear frequently in exams, so practice substituting values into the formulas!
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.
1
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Mock Exam
Quiz
Flashcards
Essay
Similar content
Electricity & Energy Concepts
Explore key concepts in electricity and energy, including resistance, Ohm's Law, energy resources, and the principles of circuits. This summary covers essential topics for GCSE combined science AQA Trilogy, providing a clear understanding of how electrical systems operate and the conservation of energy. Ideal for exam preparation and revision.
Physics9
Understanding Work and Energy
Explore the principles of work and energy in physics, including the work done formula, energy transfers, and examples of energy stores. This summary covers key concepts such as mechanical work, conservation of energy, and the Work-Energy Principle, providing a clear understanding for students. Ideal for exam preparation and quick reference.
Physics9
Understanding Energy Transfers
Explore the concept of energy transfers, including mechanical work, electrical work, heating, and radiation. This summary provides insights into energy conversion processes and energy transfer diagrams, illustrating how energy moves between different stores in various systems. Ideal for students studying physics concepts related to energy transformation.
Physics9
Energy Storage & Transfer
Explore the various forms of energy storage and transfer, including kinetic, potential, thermal, and chemical energy. Understand the law of conservation of energy and how energy is transformed within systems. This summary includes energy diagrams and Sankey diagrams to illustrate energy transfers effectively.
Physics9
Energy Flow Systems
Explore the fundamentals of energy flow diagrams, including energy stores, pathways, and transfers. This summary covers key concepts such as heating, electrical transfer, and the eight energy stores, providing a clear understanding of how energy is measured and transformed in various systems. Ideal for students studying energy principles in physics.
Physics9
Energy Transfers in Physics
Explore the principles of energy transfer, including gravitational potential energy, kinetic energy, and elastic potential energy. This summary covers key concepts such as work done, efficiency, and the impact of friction on energy dissipation. Ideal for GCSE AQA Physics students seeking to understand energy transformations and conservation.
Physics9
Most popular content: Elastic Potential Energy
Most popular content in Physics
Most popular content
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