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30 Dec 2025
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GCSE Physics Revision Guide: Key Physics Topics
Isha Patel
@ishx_0119
1 / 4
Scalars, Vectors and Force Basics
Think of scalars as simple measurements with just size - like your mass (70kg) or temperature (20°C). Vectors are more complex because they need both size and direction, like velocity or force.
Here's the key difference: speed is scalar (just "how fast"), but velocity is vector ("how fast and in which direction"). Same goes for distance (scalar) versus displacement (vector with direction).
Forces are basically pushes or pulls that can change an object's shape, speed, or direction. You've got contact forces (like friction when you slide down a slope) and non-contact forces (like gravity pulling you down even when you're jumping).
Quick Tip: Remember that force is measured in newtons (N), where 1kN = 1,000N and 1MN = 1,000,000N.
Weight, Resultant Forces and Work Done
Your weight isn't the same as your mass - weight is gravity pulling on your mass. The formula is simple: weight = mass × gravitational field strength. Your mass stays the same on Mars, but your weight changes because gravity is different there.
When multiple forces act on an object, you can replace them with one resultant force that has the same effect. Free body diagrams help you visualise all the forces, whilst resolving forces involves breaking them into horizontal and vertical components using triangles or parallelograms.
Work done happens when a force moves something: W = F × s . One joule equals one newton moving something one metre. Crucially, if nothing moves, no work is done - even if you're pushing really hard against a wall!
Remember: Work and energy have the same units (joules) because when work is done, energy gets transferred.
Forces and Elasticity
You need at least two forces to change an object's shape - one force can only change speed or direction. Think about stretching a spring: you pull one end whilst something holds the other end.
Elastic deformation means the object returns to its original shape (like a proper spring). Inelastic deformation means it stays permanently stretched or bent. Hooke's Law gives us F = k × e, where k is the spring constant (how stiff the spring is) and e is the extension.
The elastic potential energy stored in a stretched spring is Ee = ½ke². This energy is only stored during elastic deformation - if you stretch something too far past its limit of proportionality, it won't store energy properly anymore.
Key Point: A large spring constant means the spring is really stiff and hard to stretch - think car suspension versus a slinky toy.
Moments, Levers and Gears
The moment is the turning effect of a force around a pivot point. You can get a bigger turning effect by applying more force or by positioning that force further from the pivot: M = F × d.
The principle of moments is brilliant for understanding balance: when something is in equilibrium, clockwise moments equal anticlockwise moments. This is why you can lift someone heavier than you on a seesaw by sitting further from the middle.
Stability depends on having a wide base and keeping the centre of mass low. Gears work by transferring turning effects - a larger output gear gives more turning force than the input gear, but the force between the gear teeth is always equal and opposite.
Real-world Application: Spanners, scissors, bottle openers and bike gears all use these moment principles to make tasks easier.
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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
GCSE Physics Revision Guide: Key Physics Topics
Isha Patel
@ishx_0119
Physics gets much easier once you understand the difference between scalars and vectors, and how forces work in the real world. This guide covers everything from basic measurements to complex force calculations, plus some brilliant applications like levers and springs... Show more
Scalars, Vectors and Force Basics
Think of scalars as simple measurements with just size - like your mass (70kg) or temperature (20°C). Vectors are more complex because they need both size and direction, like velocity or force.
Here's the key difference: speed is scalar (just "how fast"), but velocity is vector ("how fast and in which direction"). Same goes for distance (scalar) versus displacement (vector with direction).
Forces are basically pushes or pulls that can change an object's shape, speed, or direction. You've got contact forces (like friction when you slide down a slope) and non-contact forces (like gravity pulling you down even when you're jumping).
Quick Tip: Remember that force is measured in newtons (N), where 1kN = 1,000N and 1MN = 1,000,000N.
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Weight, Resultant Forces and Work Done
Your weight isn't the same as your mass - weight is gravity pulling on your mass. The formula is simple: weight = mass × gravitational field strength. Your mass stays the same on Mars, but your weight changes because gravity is different there.
When multiple forces act on an object, you can replace them with one resultant force that has the same effect. Free body diagrams help you visualise all the forces, whilst resolving forces involves breaking them into horizontal and vertical components using triangles or parallelograms.
Work done happens when a force moves something: W = F × s . One joule equals one newton moving something one metre. Crucially, if nothing moves, no work is done - even if you're pushing really hard against a wall!
Remember: Work and energy have the same units (joules) because when work is done, energy gets transferred.
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Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Forces and Elasticity
You need at least two forces to change an object's shape - one force can only change speed or direction. Think about stretching a spring: you pull one end whilst something holds the other end.
Elastic deformation means the object returns to its original shape (like a proper spring). Inelastic deformation means it stays permanently stretched or bent. Hooke's Law gives us F = k × e, where k is the spring constant (how stiff the spring is) and e is the extension.
The elastic potential energy stored in a stretched spring is Ee = ½ke². This energy is only stored during elastic deformation - if you stretch something too far past its limit of proportionality, it won't store energy properly anymore.
Key Point: A large spring constant means the spring is really stiff and hard to stretch - think car suspension versus a slinky toy.
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Moments, Levers and Gears
The moment is the turning effect of a force around a pivot point. You can get a bigger turning effect by applying more force or by positioning that force further from the pivot: M = F × d.
The principle of moments is brilliant for understanding balance: when something is in equilibrium, clockwise moments equal anticlockwise moments. This is why you can lift someone heavier than you on a seesaw by sitting further from the middle.
Stability depends on having a wide base and keeping the centre of mass low. Gears work by transferring turning effects - a larger output gear gives more turning force than the input gear, but the force between the gear teeth is always equal and opposite.
Real-world Application: Spanners, scissors, bottle openers and bike gears all use these moment principles to make tasks easier.
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.
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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