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Eushra Rahman
11/16/2025
AP Physics 1
Kinematics and 2D review
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Nov 16, 2025
•
Understanding Kinematics and 2D Motion - AP Physics 1 Guide
Eushra Rahman
@eushrarahman_mvbn
1 / 5
Kinematics Fundamentals
Kinematics deals with the mathematics of motion without considering forces. Remember that speed is a scalar quantity (magnitude only), while velocity is a vector (has both magnitude and direction). Vectors are added head-to-tail, and the order doesn't matter.
The essential kinematic equations you need to know are:
- Average velocity: v̄ = d/t
- Average acceleration: ā = v/t
- Distance with acceleration: d = ½at² + vᵢt
- Final velocity squared: vf² = vᵢ² + 2ad
- Final velocity: vf = vᵢ + at
- Average velocity: v̄ = /2
In projectile motion, remember that horizontal and vertical motions are independent. There's constant velocity in the horizontal direction (no acceleration) and constant acceleration due to gravity in the vertical direction. The path of a projectile forms a parabola, with maximum range occurring at a 45° angle.
💡 For projectile problems, always separate horizontal and vertical components! The horizontal velocity remains constant while the vertical velocity changes due to gravity.
The range equation for projectile motion is: range = (vᵢ²sin2θ)/g
Newton's Laws and Friction
Newton's laws describe the relationship between forces and motion. Force is simply a push or pull, measured in newtons . An interesting fact: an apple weighs approximately 1 N!
The three fundamental laws are:
- 1st Law (Inertia): Objects at rest stay at rest, and objects in motion stay in motion at constant speed in a straight line unless acted upon by a force. The greater the mass, the greater the inertia.
- 2nd Law: F = ma (Force equals mass times acceleration)
- 3rd Law: For every action, there's an equal and opposite reaction
When dealing with friction problems, remember that static friction (μₛ) applies when an object isn't moving, while kinetic friction (μₖ) applies when it's sliding. The maximum static friction is calculated as Fₛ = μₛFₙ, where Fₙ is the normal force.
💡 If an object has constant velocity, the net force must be zero ! This is a direct application of Newton's 1st law and can simplify many problems.
For an object to start moving, you need to apply a force greater than the maximum static friction. Once moving, the friction force decreases to kinetic friction.
Gravitation and Springs
The force of gravity between two objects is given by Fg = Gm₁m₂/r² where G is the gravitational constant, m₁ and m₂ are the masses, and r is the distance between them. On Earth's surface, we simplify this to Fg = mg. Gravity follows an inverse square relationship - double the distance, and the force becomes ¼ as strong.
Spring force is described by Hooke's Law: F = kx, where k is the spring constant and x is the displacement from equilibrium. The potential energy stored in a spring is PE = ½kx². Understanding the relationship between force, displacement, and velocity in a spring is crucial:
- At maximum displacement: force is maximum, acceleration is maximum, but velocity is zero
- At equilibrium position: force is zero, acceleration is zero, but velocity is maximum
When solving inclined plane problems, remember to break forces into components. As the incline gets steeper, the normal force decreases, which reduces friction. The component of gravity parallel to the slope (mgsinθ) causes objects to slide, while the perpendicular component (mgcosθ) creates the normal force.
💡 When analyzing forces on an inclined plane, the sine component (mgsinθ) makes things slide while the cosine component (mgcosθ) determines the normal force and friction!
Key Concepts in 2D Motion
In 2D motion, it's crucial to keep horizontal (x) and vertical (y) components separate. Even though they're happening simultaneously, they don't affect each other. Vertical acceleration does not affect horizontal speed, and horizontal speed does not affect vertical acceleration.
This explains why two objects - one dropped straight down and one projected horizontally - will hit the ground at the same time if dropped from the same height. The horizontal motion doesn't change the fact that gravity pulls both objects down at the same rate.
When comparing projectiles with different initial velocities:
- Objects with the same vertical component but different horizontal components will land at the same time
- Objects launched from the same height with different initial velocities will travel different horizontal distances
- The horizontal distance traveled can be calculated as Δx = v√ for horizontal launches
💡 The horizontal distance a projectile travels depends more on its velocity than on height! This is why increasing the speed of a projectile has a greater effect on range than increasing its height.
Remember that the time an object is in the air depends only on its vertical motion, but the distance it travels horizontally depends on both its horizontal velocity and that time.
Motion Graphs and Problem-Solving
Motion graphs provide visual representations of position, velocity, and acceleration. For these graphs:
- The slope of a position-time graph gives velocity
- The area under a velocity-time graph gives displacement
- The slope of a velocity-time graph gives acceleration
When solving problems involving relative motion (like objects moving in flowing water), remember that the total velocity is the vector sum of the individual velocities. For an object in a flowing medium: vₜₒₜₐₗ = vₒbⱼₑcₜ + vₘₑdᵢᵤₘ
The key kinematic equations for problem-solving are:
- vf = vi + at
- vf² = vi² + 2ad
- d = ½at² + vit (These equations assume initial time is zero)
💡 When in doubt about which approach to use for a physics problem, write down what you know, identify what you're looking for, and select the equation that connects them with the fewest unknown variables!
For any motion problem, start by clearly identifying the known variables and what you're solving for, then select the appropriate kinematic equation that will get you to the answer most efficiently.
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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 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 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 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 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 Kinematics and 2D Motion - AP Physics 1 Guide
Eushra Rahman
@eushrarahman_mvbn
Kinematics and 2D motion are fundamental concepts in physics that describe how objects move. This summary covers the essential principles of kinematics, projectile motion, Newton's laws, springs, and various motion scenarios that will help you understand these topics for tests... Show more
Kinematics Fundamentals
Kinematics deals with the mathematics of motion without considering forces. Remember that speed is a scalar quantity (magnitude only), while velocity is a vector (has both magnitude and direction). Vectors are added head-to-tail, and the order doesn't matter.
The essential kinematic equations you need to know are:
- Average velocity: v̄ = d/t
- Average acceleration: ā = v/t
- Distance with acceleration: d = ½at² + vᵢt
- Final velocity squared: vf² = vᵢ² + 2ad
- Final velocity: vf = vᵢ + at
- Average velocity: v̄ = /2
In projectile motion, remember that horizontal and vertical motions are independent. There's constant velocity in the horizontal direction (no acceleration) and constant acceleration due to gravity in the vertical direction. The path of a projectile forms a parabola, with maximum range occurring at a 45° angle.
💡 For projectile problems, always separate horizontal and vertical components! The horizontal velocity remains constant while the vertical velocity changes due to gravity.
The range equation for projectile motion is: range = (vᵢ²sin2θ)/g
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Newton's Laws and Friction
Newton's laws describe the relationship between forces and motion. Force is simply a push or pull, measured in newtons . An interesting fact: an apple weighs approximately 1 N!
The three fundamental laws are:
- 1st Law (Inertia): Objects at rest stay at rest, and objects in motion stay in motion at constant speed in a straight line unless acted upon by a force. The greater the mass, the greater the inertia.
- 2nd Law: F = ma (Force equals mass times acceleration)
- 3rd Law: For every action, there's an equal and opposite reaction
When dealing with friction problems, remember that static friction (μₛ) applies when an object isn't moving, while kinetic friction (μₖ) applies when it's sliding. The maximum static friction is calculated as Fₛ = μₛFₙ, where Fₙ is the normal force.
💡 If an object has constant velocity, the net force must be zero ! This is a direct application of Newton's 1st law and can simplify many problems.
For an object to start moving, you need to apply a force greater than the maximum static friction. Once moving, the friction force decreases to kinetic friction.
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Gravitation and Springs
The force of gravity between two objects is given by Fg = Gm₁m₂/r² where G is the gravitational constant, m₁ and m₂ are the masses, and r is the distance between them. On Earth's surface, we simplify this to Fg = mg. Gravity follows an inverse square relationship - double the distance, and the force becomes ¼ as strong.
Spring force is described by Hooke's Law: F = kx, where k is the spring constant and x is the displacement from equilibrium. The potential energy stored in a spring is PE = ½kx². Understanding the relationship between force, displacement, and velocity in a spring is crucial:
- At maximum displacement: force is maximum, acceleration is maximum, but velocity is zero
- At equilibrium position: force is zero, acceleration is zero, but velocity is maximum
When solving inclined plane problems, remember to break forces into components. As the incline gets steeper, the normal force decreases, which reduces friction. The component of gravity parallel to the slope (mgsinθ) causes objects to slide, while the perpendicular component (mgcosθ) creates the normal force.
💡 When analyzing forces on an inclined plane, the sine component (mgsinθ) makes things slide while the cosine component (mgcosθ) determines the normal force and friction!
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Improve your grades
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Key Concepts in 2D Motion
In 2D motion, it's crucial to keep horizontal (x) and vertical (y) components separate. Even though they're happening simultaneously, they don't affect each other. Vertical acceleration does not affect horizontal speed, and horizontal speed does not affect vertical acceleration.
This explains why two objects - one dropped straight down and one projected horizontally - will hit the ground at the same time if dropped from the same height. The horizontal motion doesn't change the fact that gravity pulls both objects down at the same rate.
When comparing projectiles with different initial velocities:
- Objects with the same vertical component but different horizontal components will land at the same time
- Objects launched from the same height with different initial velocities will travel different horizontal distances
- The horizontal distance traveled can be calculated as Δx = v√ for horizontal launches
💡 The horizontal distance a projectile travels depends more on its velocity than on height! This is why increasing the speed of a projectile has a greater effect on range than increasing its height.
Remember that the time an object is in the air depends only on its vertical motion, but the distance it travels horizontally depends on both its horizontal velocity and that time.
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Motion Graphs and Problem-Solving
Motion graphs provide visual representations of position, velocity, and acceleration. For these graphs:
- The slope of a position-time graph gives velocity
- The area under a velocity-time graph gives displacement
- The slope of a velocity-time graph gives acceleration
When solving problems involving relative motion (like objects moving in flowing water), remember that the total velocity is the vector sum of the individual velocities. For an object in a flowing medium: vₜₒₜₐₗ = vₒbⱼₑcₜ + vₘₑdᵢᵤₘ
The key kinematic equations for problem-solving are:
- vf = vi + at
- vf² = vi² + 2ad
- d = ½at² + vit (These equations assume initial time is zero)
💡 When in doubt about which approach to use for a physics problem, write down what you know, identify what you're looking for, and select the equation that connects them with the fewest unknown variables!
For any motion problem, start by clearly identifying the known variables and what you're solving for, then select the appropriate kinematic equation that will get you to the answer most efficiently.
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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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 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 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 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 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