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Updated Mar 14, 2026
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Understanding Different Types of Forces
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What Are Forces?
Think of forces as the invisible hands of physics - you can't see them, but you definitely see what they do! A force is simply a push or a pull that can make objects start moving, stop moving, change direction, or even change shape. We measure forces in Newtons (N), named after the famous scientist Isaac Newton.
Forces come in two main types. Contact forces happen when objects are actually touching each other, like when you push a door or rub your hands together. Non-contact forces can affect objects without touching them - gravity pulling on you right now is a perfect example.
Here's something crucial for your exams: forces can be balanced or unbalanced. When forces are balanced (equal in size but opposite in direction), nothing changes - objects stay still or keep moving at the same speed. When forces are unbalanced, that's when the action happens - things speed up, slow down, or change direction.
Remember: You experience hundreds of forces every day - from gravity keeping your feet on the ground to friction helping you walk without slipping!
Gravity - The Ultimate Pulling Force
Gravity is probably the most important force you'll ever encounter - it's literally keeping you grounded right now! This non-contact force pulls objects towards each other, and the stronger the mass of an object, the stronger its gravitational pull. Earth has massive mass, so it pulls everything towards its centre.
Here's where students often get confused: mass and weight are completely different things. Your mass (measured in kg) is the amount of 'stuff' you're made of - it stays the same whether you're on Earth, the Moon, or floating in space. Your weight (measured in Newtons) is the force of gravity pulling on your mass, and it changes depending on where you are.
Think about it this way: if you went to the Moon, you'd have the same mass but weigh much less because the Moon's gravity is weaker than Earth's. That's why astronauts can bounce around so easily up there!
Exam Tip: Questions about mass vs weight are guaranteed to appear - mass is in kg, weight is the gravitational force in Newtons!
Friction - The Force That Fights Movement
Friction is the rebel of the force world - it always tries to oppose motion! This contact force happens when two surfaces rub against each other, and it always acts in the opposite direction to movement. Without friction, you'd slide helplessly across the floor like you're on ice.
The amount of friction depends on two key things. First, the type of surfaces involved - rough surfaces like sandpaper create loads of friction, while smooth surfaces like polished floors create very little. Second, how hard the surfaces press together - heavier objects create more friction because they press down harder.
Friction can be your best friend or your worst enemy. It's brilliant when you need grip (like football boots on grass or car brakes stopping you safely), but it's annoying when it wears out moving parts in engines or makes it harder to push heavy objects.
Real-world Connection: Next time you're walking, think about how friction between your shoes and the ground stops you from slipping with every step!
Air Resistance - Friction's Flying Cousin
Air resistance (also called drag) is basically friction's cousin that works in the air. When objects move through air, tiny air particles bash into them, creating a contact force that opposes the motion. It's like trying to run through water - the faster you go, the harder it pushes back.
Two main factors affect how much air resistance you experience. Speed is the big one - stick your hand out of a car window and you'll feel how air resistance increases with speed. The shape and size of the object matter too - that's why parachutes work so well with their huge surface area catching air, while sports cars are streamlined to slice through air easily.
Air resistance explains why feathers fall slowly while stones drop quickly, and why cyclists crouch down to go faster. It's constantly working against moving objects, gradually slowing them down unless another force keeps pushing them forward.
Think About It: Birds have naturally streamlined shapes to reduce air resistance - evolution's way of making flight more efficient!
Forces Working Together - Real Examples
Let's see how these forces team up in everyday situations you'll recognise. When a book sits on your desk, gravity pulls it downward while the table pushes up with equal force - these balanced forces keep the book perfectly still.
Kicking a football shows unbalanced forces in action. Your foot applies a pushing force that gets the ball moving, gravity curves its path downward, and air resistance gradually slows it down. All three forces work together to create that familiar arc through the air.
When you're cycling and need to brake, friction becomes the hero. The brake pads squeeze your wheels, creating friction that opposes your forward motion. Combined with air resistance, these forces bring you safely to a stop.
Exam Success: Always remember to state the direction of forces - gravity pulls down, friction opposes motion, and air resistance works against the direction you're moving!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
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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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Understanding Different Types of Forces
Ever wonder why things fall down instead of up, or why you can't slide forever on a smooth floor? Forces are everywhere around us - they're the invisible pushes and pulls that make everything move, stop, or change direction. Understanding... Show more
What Are Forces?
Think of forces as the invisible hands of physics - you can't see them, but you definitely see what they do! A force is simply a push or a pull that can make objects start moving, stop moving, change direction, or even change shape. We measure forces in Newtons (N), named after the famous scientist Isaac Newton.
Forces come in two main types. Contact forces happen when objects are actually touching each other, like when you push a door or rub your hands together. Non-contact forces can affect objects without touching them - gravity pulling on you right now is a perfect example.
Here's something crucial for your exams: forces can be balanced or unbalanced. When forces are balanced (equal in size but opposite in direction), nothing changes - objects stay still or keep moving at the same speed. When forces are unbalanced, that's when the action happens - things speed up, slow down, or change direction.
Remember: You experience hundreds of forces every day - from gravity keeping your feet on the ground to friction helping you walk without slipping!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Gravity - The Ultimate Pulling Force
Gravity is probably the most important force you'll ever encounter - it's literally keeping you grounded right now! This non-contact force pulls objects towards each other, and the stronger the mass of an object, the stronger its gravitational pull. Earth has massive mass, so it pulls everything towards its centre.
Here's where students often get confused: mass and weight are completely different things. Your mass (measured in kg) is the amount of 'stuff' you're made of - it stays the same whether you're on Earth, the Moon, or floating in space. Your weight (measured in Newtons) is the force of gravity pulling on your mass, and it changes depending on where you are.
Think about it this way: if you went to the Moon, you'd have the same mass but weigh much less because the Moon's gravity is weaker than Earth's. That's why astronauts can bounce around so easily up there!
Exam Tip: Questions about mass vs weight are guaranteed to appear - mass is in kg, weight is the gravitational force in Newtons!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Friction - The Force That Fights Movement
Friction is the rebel of the force world - it always tries to oppose motion! This contact force happens when two surfaces rub against each other, and it always acts in the opposite direction to movement. Without friction, you'd slide helplessly across the floor like you're on ice.
The amount of friction depends on two key things. First, the type of surfaces involved - rough surfaces like sandpaper create loads of friction, while smooth surfaces like polished floors create very little. Second, how hard the surfaces press together - heavier objects create more friction because they press down harder.
Friction can be your best friend or your worst enemy. It's brilliant when you need grip (like football boots on grass or car brakes stopping you safely), but it's annoying when it wears out moving parts in engines or makes it harder to push heavy objects.
Real-world Connection: Next time you're walking, think about how friction between your shoes and the ground stops you from slipping with every step!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Air Resistance - Friction's Flying Cousin
Air resistance (also called drag) is basically friction's cousin that works in the air. When objects move through air, tiny air particles bash into them, creating a contact force that opposes the motion. It's like trying to run through water - the faster you go, the harder it pushes back.
Two main factors affect how much air resistance you experience. Speed is the big one - stick your hand out of a car window and you'll feel how air resistance increases with speed. The shape and size of the object matter too - that's why parachutes work so well with their huge surface area catching air, while sports cars are streamlined to slice through air easily.
Air resistance explains why feathers fall slowly while stones drop quickly, and why cyclists crouch down to go faster. It's constantly working against moving objects, gradually slowing them down unless another force keeps pushing them forward.
Think About It: Birds have naturally streamlined shapes to reduce air resistance - evolution's way of making flight more efficient!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Forces Working Together - Real Examples
Let's see how these forces team up in everyday situations you'll recognise. When a book sits on your desk, gravity pulls it downward while the table pushes up with equal force - these balanced forces keep the book perfectly still.
Kicking a football shows unbalanced forces in action. Your foot applies a pushing force that gets the ball moving, gravity curves its path downward, and air resistance gradually slows it down. All three forces work together to create that familiar arc through the air.
When you're cycling and need to brake, friction becomes the hero. The brake pads squeeze your wheels, creating friction that opposes your forward motion. Combined with air resistance, these forces bring you safely to a stop.
Exam Success: Always remember to state the direction of forces - gravity pulls down, friction opposes motion, and air resistance works against the direction you're moving!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the 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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4.6/5
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4.7/5
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user