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103
•
Updated 19 Feb 2026
•
raniya
@raniya
Understanding motion is essential for physics - whether you're watching... Show more
Speed tells you how fast something is moving, and it's surprisingly straightforward to work out. You measure it in metres per second , which makes sense when you think about it - you're seeing how many metres something covers each second.
Speed is what we call a scalar quantity, meaning it only cares about the size of the measurement, not the direction. Whether you're running towards the school or away from it, if you're covering 5 metres every second, your speed is 5 m/s.
The formula is dead simple: average speed = distance ÷ time. So if you walk 100 metres in 50 seconds, your average speed is 2 m/s. Remember, this gives you the average because you probably didn't walk at exactly the same pace the whole time.
Quick Tip: The triangle method works brilliantly here - put distance on top, speed and time on the bottom, then cover what you want to find!
Velocity is basically speed's more sophisticated cousin - it cares about direction as well as how fast you're going. You still measure it in metres per second , but now the direction matters loads.
This makes velocity a vector quantity because it has both size (how fast) and direction (which way). Think of it like this: if you're walking towards the front of the classroom at 2 m/s, that's different from walking towards the back at 2 m/s, even though your speed is the same.
Positive velocity means you're moving forwards (in whatever direction you've decided is 'forwards'). Negative velocity means you're moving backwards. It's all about the reference point you choose - there's no universal 'forwards' in physics!
Remember: Two objects can have the same speed but completely different velocities if they're heading in opposite directions.
Acceleration measures how quickly velocity changes, and it's measured in metres per second squared . That weird unit makes sense when you think about it - you're measuring how many m/s the velocity changes each second.
Like velocity, acceleration is a vector quantity because direction matters. When you're in a car that speeds up, slows down, or goes round a corner, you're experiencing acceleration in different ways.
Positive acceleration means velocity is increasing - you're speeding up in the forward direction or slowing down in the backward direction. Negative acceleration (also called deceleration) means velocity is decreasing - you're slowing down if moving forwards, or speeding up if moving backwards.
Real-world connection: When you feel pushed back in your seat as a car accelerates, or thrown forward when it brakes, you're experiencing the effects of acceleration!
These concepts pop up constantly in physics exams, so getting them sorted now will save you loads of hassle later. Scalar quantities (like speed and distance) only have size, whilst vector quantities (like velocity, acceleration, and displacement) have both size and direction.
Distance uses metres (m), whilst speed, velocity use metres per second , and acceleration uses metres per second squared . The gradient of a distance-time graph gives you speed - the steeper the line, the faster the movement.
Displacement is like distance but cares about direction - it's how far you end up from where you started, in a straight line. Negative values in physics usually mean 'opposite direction' - negative acceleration means slowing down, negative velocity means moving backwards, negative displacement means you're on the opposite side of your starting point.
Exam tip: Always include units in your answers and remember that negative values aren't 'wrong' - they're just telling you about direction!
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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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 Knowunity AI. 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 Knowunity AI. 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
raniya
@raniya
Understanding motion is essential for physics - whether you're watching a football fly through the air or calculating how fast you cycle to school. Let's break down the key concepts of speed, velocity, and acceleration that'll help you master motion... Show more
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Speed tells you how fast something is moving, and it's surprisingly straightforward to work out. You measure it in metres per second , which makes sense when you think about it - you're seeing how many metres something covers each second.
Speed is what we call a scalar quantity, meaning it only cares about the size of the measurement, not the direction. Whether you're running towards the school or away from it, if you're covering 5 metres every second, your speed is 5 m/s.
The formula is dead simple: average speed = distance ÷ time. So if you walk 100 metres in 50 seconds, your average speed is 2 m/s. Remember, this gives you the average because you probably didn't walk at exactly the same pace the whole time.
Quick Tip: The triangle method works brilliantly here - put distance on top, speed and time on the bottom, then cover what you want to find!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Velocity is basically speed's more sophisticated cousin - it cares about direction as well as how fast you're going. You still measure it in metres per second , but now the direction matters loads.
This makes velocity a vector quantity because it has both size (how fast) and direction (which way). Think of it like this: if you're walking towards the front of the classroom at 2 m/s, that's different from walking towards the back at 2 m/s, even though your speed is the same.
Positive velocity means you're moving forwards (in whatever direction you've decided is 'forwards'). Negative velocity means you're moving backwards. It's all about the reference point you choose - there's no universal 'forwards' in physics!
Remember: Two objects can have the same speed but completely different velocities if they're heading in opposite directions.
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Acceleration measures how quickly velocity changes, and it's measured in metres per second squared . That weird unit makes sense when you think about it - you're measuring how many m/s the velocity changes each second.
Like velocity, acceleration is a vector quantity because direction matters. When you're in a car that speeds up, slows down, or goes round a corner, you're experiencing acceleration in different ways.
Positive acceleration means velocity is increasing - you're speeding up in the forward direction or slowing down in the backward direction. Negative acceleration (also called deceleration) means velocity is decreasing - you're slowing down if moving forwards, or speeding up if moving backwards.
Real-world connection: When you feel pushed back in your seat as a car accelerates, or thrown forward when it brakes, you're experiencing the effects of acceleration!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
These concepts pop up constantly in physics exams, so getting them sorted now will save you loads of hassle later. Scalar quantities (like speed and distance) only have size, whilst vector quantities (like velocity, acceleration, and displacement) have both size and direction.
Distance uses metres (m), whilst speed, velocity use metres per second , and acceleration uses metres per second squared . The gradient of a distance-time graph gives you speed - the steeper the line, the faster the movement.
Displacement is like distance but cares about direction - it's how far you end up from where you started, in a straight line. Negative values in physics usually mean 'opposite direction' - negative acceleration means slowing down, negative velocity means moving backwards, negative displacement means you're on the opposite side of your starting point.
Exam tip: Always include units in your answers and remember that negative values aren't 'wrong' - they're just telling you about direction!
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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Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
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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 Knowunity AI. 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 Knowunity AI. 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
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