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30 Dec 2025
•
Understanding Scalar and Vector Quantities
S
saraabdeljaber30
@saraabdeljaber3
1 / 10
Introduction to Scalar and Vector Quantities
Every measurement in physics fits into one of two camps, and getting this right will make calculations so much easier. Scalar quantities are straightforward - they're just numbers with units that tell you "how much" of something there is.
Vector quantities are more complex because they need two pieces of information: the size (magnitude) and the direction. Think of it like giving directions to a mate - saying "walk 100 metres" isn't enough, you need "walk 100 metres north" to be useful.
Quick Check: Temperature is always scalar (20°C), but force is always vector (200N to the right) because forces push or pull in specific directions.
Temperature and Force Examples
Temperature is your classic scalar quantity because it doesn't matter which way you're facing when it's 20°C in your room. There's no directional component to temperature - it's just a magnitude with units.
Force works completely differently because every push or pull happens in a specific direction. When you see forces drawn as arrows, the arrow's length shows the magnitude (like 400N) and the arrow's direction shows which way the force acts.
This is why force calculations can get tricky - you can't just add forces together like regular numbers because their directions matter massively.
Speed vs Velocity: The Classic Confusion
Here's where loads of students get caught out: speed and velocity aren't the same thing. Speed is scalar - your car's speedometer showing 30 m/s tells you the magnitude but nothing about direction.
Velocity includes direction, so "30 m/s due north" is a proper velocity. Same speed, but now you know exactly which way you're heading.
This distinction becomes crucial in calculations because velocities can cancel each other out if they're in opposite directions, but speeds just add up regardless of direction.
Real-world tip: When describing motion in physics problems, always check if they want speed (just the number) or velocity (number plus direction).
Distance vs Displacement: The Journey Matters
Distance measures the total path you've travelled - every step, turn, and detour gets added up. It's scalar because you're just totalling up lengths without worrying about direction.
Displacement is much smarter - it only cares about your starting point and ending point. If you walk 2.1 km around a park but end up just 1.1 km from where you started, that's your displacement.
Displacement can even be zero if you return to your starting point, even if you've walked for miles. This makes displacement calculations really useful for understanding overall motion.
Mass vs Weight: Not What You Think
Mass is scalar and never changes - you've got the same amount of matter whether you're on Earth or floating in space. Your bathroom scales measure mass in kilograms.
Weight is the force of gravity pulling on your mass, making it a vector that always points downward (toward the planet's centre). Weight changes depending on gravity strength, so you'd weigh less on the Moon.
This is why astronauts are "weightless" in space but still have the same mass. Understanding this difference helps explain why weight is measured in Newtons (force units) whilst mass uses kilograms.
Memory trick: Mass stays constant everywhere, but weight depends on where you are because it's a gravitational force.
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4.9/5
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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
Understanding Scalar and Vector Quantities
S
saraabdeljaber30
@saraabdeljaber3
Physics measurements fall into two crucial categories that you need to master. Scalar quantities only have size (magnitude), whilst vector quantities have both size and direction - understanding this difference is essential for getting physics problems right.
Introduction to Scalar and Vector Quantities
Every measurement in physics fits into one of two camps, and getting this right will make calculations so much easier. Scalar quantities are straightforward - they're just numbers with units that tell you "how much" of something there is.
Vector quantities are more complex because they need two pieces of information: the size (magnitude) and the direction. Think of it like giving directions to a mate - saying "walk 100 metres" isn't enough, you need "walk 100 metres north" to be useful.
Quick Check: Temperature is always scalar (20°C), but force is always vector (200N to the right) because forces push or pull in specific directions.
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Temperature and Force Examples
Temperature is your classic scalar quantity because it doesn't matter which way you're facing when it's 20°C in your room. There's no directional component to temperature - it's just a magnitude with units.
Force works completely differently because every push or pull happens in a specific direction. When you see forces drawn as arrows, the arrow's length shows the magnitude (like 400N) and the arrow's direction shows which way the force acts.
This is why force calculations can get tricky - you can't just add forces together like regular numbers because their directions matter massively.
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Speed vs Velocity: The Classic Confusion
Here's where loads of students get caught out: speed and velocity aren't the same thing. Speed is scalar - your car's speedometer showing 30 m/s tells you the magnitude but nothing about direction.
Velocity includes direction, so "30 m/s due north" is a proper velocity. Same speed, but now you know exactly which way you're heading.
This distinction becomes crucial in calculations because velocities can cancel each other out if they're in opposite directions, but speeds just add up regardless of direction.
Real-world tip: When describing motion in physics problems, always check if they want speed (just the number) or velocity (number plus direction).
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Distance vs Displacement: The Journey Matters
Distance measures the total path you've travelled - every step, turn, and detour gets added up. It's scalar because you're just totalling up lengths without worrying about direction.
Displacement is much smarter - it only cares about your starting point and ending point. If you walk 2.1 km around a park but end up just 1.1 km from where you started, that's your displacement.
Displacement can even be zero if you return to your starting point, even if you've walked for miles. This makes displacement calculations really useful for understanding overall motion.
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Mass vs Weight: Not What You Think
Mass is scalar and never changes - you've got the same amount of matter whether you're on Earth or floating in space. Your bathroom scales measure mass in kilograms.
Weight is the force of gravity pulling on your mass, making it a vector that always points downward (toward the planet's centre). Weight changes depending on gravity strength, so you'd weigh less on the Moon.
This is why astronauts are "weightless" in space but still have the same mass. Understanding this difference helps explain why weight is measured in Newtons (force units) whilst mass uses kilograms.
Memory trick: Mass stays constant everywhere, but weight depends on where you are because it's a gravitational force.
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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?
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Is Knowunity really free of charge?
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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