JEE Main Physics Rotational Motion Notes (Free PDF Download)

While going through the previous year's papers of JEE Main, you can find 2 to 4 questions asked from this chapter. Check out how many questions were asked from the Rotational Motion chapter in the last five years of JEE Main exams. Look at the table below for more information.

Take the chance to elevate your preparation with our Rotational Motion Notes. It covers the whole JEE Main Physics syllabus and you can download it for FREE.

JEE Main 2025: Must-ReviseTopics in Rotational Motion

Let's focus on the key topics you should review in Rotational Motion. These important topics can make a real difference in your preparation. Mastering them will give you a strong edge in the upcoming exam. Let's dive into the must-revise topics to help you shine in JEE Main 2025.

• Moment of Inertia

• Angular Velocity and Acceleration

• Torque and Rotational Equilibrium

• Angular Momentum

• Kinematics of Rotational Motion

• Rolling Motion

• Rotational Kinetic Energy

• Combined Translational and Rotational Motion

• Angular Momentum and Torque Relationships

• Conservation of Energy in Rotational Motion

• Angular Momentum and Its Conservation

• Rotational Dynamics

• Angular Impulse and Collision

• Rotational Work and Power

Important JEE Rotational Motion Formulas to Learn With Notes

Equations are more than just symbols –They're your secret code to solve problems in Physics. When you understand formulas, you can easily handle tricky ideas and feel more sure of yourself.  Use the equation with JEE Main Physics Revision notes to improve studying. Check out our Physics formula pages and begin your journey to prepare for JEE Main now!

1. Center of a mass of a two-particle system:  Center of mass of a two-particle system is the balance point, considering their masses and positions in space. The formula is:

Center of Mass $= \dfrac{(m_1 r_1 + m_2  r_2)}{(m_1 + m_2)}$

Here, 'm₁' and 'm₂' are the masses, and 'r₁' and 'r₂' are their positions. It's crucial for understanding rotational motion, equilibrium, and stability.

2. Center of the mass of rigid body; Basic concepts of a rotational motion; a moment of force; torque: 

Center of Mass of a Rigid Body: It's the balance point for an entire object, considering mass distribution. It's calculated by finding where the body effectively balances.

Rotational Motion Basics: It's about how objects spin and move in circles. This motion is influenced by torque, a twisting force. Torque is calculated as:

Torque (τ) = Force (F) × Lever Arm (r), 

where the lever arm is the distance from the pivot point to the force's line of action. 

Torque is crucial in determining how an object rotates or balances, a fundamental concept in rotational motion study.

3. Angular Momentum: Angular momentum measures an object's rotation. It depends on the moment of inertia (mass distribution) and angular velocity (spin speed). The formula is $L = I \times \omega$. It explains why objects spin, stop, or change their spin, crucial for understanding rotating systems' dynamics.

4. Conservation of Angular Momentum and its applications: Similar to the conservation of linear momentum, this law applies to rotating objects. It states that in the absence of external torques, a system's total angular momentum remains constant. Essentially, if a spinning object encounters no external twisting forces, its angular momentum stays unchanged. This principle is valuable in explaining scenarios like ice skaters accelerating by pulling their limbs closer (reducing moment of inertia) and understanding celestial bodies' movements. It aids in predicting and understanding the motion of rotating objects in various situations.

5. The moment of Inertia: This is the rotational counterpart to mass in linear motion. Represented as 'I,' it assesses how an object's mass is distributed around its rotation axis. When you think of a figure skater, pulling their arms in to spin faster, it's due to a reduced moment of inertia. The moment of inertia relies on an object's shape and mass distribution, with mathematical formulas for simple shapes like rods or disks. It's pivotal for predicting an object's rotation behavior and is a fundamental concept in the study of rotational motion.

6. The radius of gyration: Picture it as a measure of mass distribution from the rotation axis. Denoted as 'k,' it's a single value summarizing an object's mass distribution, calculated with:

Radius of Gyration (k) $= \sqrt{\dfrac{\text{Moment of Inertia (I)}}{\text{Total Mass (M)}}}$

Smaller 'k' implies mass concentrated near the axis, while larger 'k' means mass spread out. This simplifies complex rotation calculations, crucial for comprehending spinning object behavior.

7. Values of moments of inertia for simple geometrical objects: These values serve as templates for how various objects rotate. For instance, a slender rod spinning around one end has a moment of inertia of $\dfrac{1}{3} (\text{mass}) (\text{length})^2$. A disk rotating about its center axis has a moment of inertia of $\dfrac{1}{2}(\text{mass})(\text{radius})^2$. Meanwhile, a hoop spinning around its central axis, like a hula hoop, has a moment of inertia of $(\text{mass})(\text{radius})^2$. These values are fundamental in predicting how objects with basic shapes behave during rotation.

8. Parallel and perpendicular axes theorems: These theorems are crucial for calculating moments of inertia in complex shapes. The parallel axes theorem allows us to find the moment of inertia around an axis parallel to (but not through) the center of mass. It involves adding the moment of inertia around the axis through the center of mass and the product of the object's mass and the square of the distance between the two axes. On the other hand, the perpendicular axes theorem relates moments of inertia for an object rotating around two perpendicular axes through the same point. It states that the moment of inertia about one axis equals the sum of moments of inertia about two other perpendicular axes. These theorems simplify complex calculations involving rotational motion.

9. Rigid body rotation equation of rotational motion: This equation, akin to Newton's second law, is tailored for rotating objects. It states that the net torque acting on an object equals the rate of change of its angular momentum. Mathematically, it's expressed as Net Torque (τ) = Rate of Change of Angular Momentum $\left(\dfrac{dL}{dt}\right)$. This equation is crucial in predicting and analyzing the behavior of rotating bodies, helping us understand how they change their angular motion when subjected to torques. It allows us to determine how they accelerate, decelerate, or maintain a constant angular velocity under the influence of various forces.

Learn With Rotational Motion Notes and Score High in JEE Main 2025

Rotational Motion is the field that involves the study of objects' rotation around an axis. The weightage of Rotational Motion in JEE Main is around 4 - 8%, and students can also expect direct questions from this section which makes it one of the scoring topics. Here are the few points that make the chapter high weightage.

Spinning into Understanding:

• Imagine a world beyond linear movement—a world where objects twirl, spin, and pivot. Welcome to the captivating realm of rotational motion!

• Just as we learned about linear motion, rotational motion introduces a dynamic twist as objects rotate around fixed axes. Get ready to unravel the magic of spinning phenomena!

The Dance of Axes and Moments:

• Picture a dancer pirouetting on a stage. Similarly, objects rotate around an axis, creating a mesmerizing ballet. This axis becomes the focal point of rotational motion.

• Ever heard of moments? Not the "take a picture" kind, but moments that describe how objects respond to forces and torques during their graceful spins.

Angular Velocity - The Spin Speedster:

• Meet angular velocity, the speedster of rotation. Just as linear velocity measures how fast an object moves in a straight line, angular velocity measures the rapidity of rotation.

• Think of a spinning top; its angular velocity defines how swiftly it twirls. The concept is as captivating as watching a top gracefully spin.

Torque: The Twisting Force:

• Torque is the superstar that orchestrates rotation. It's the force that creates the twist, making objects pivot around an axis. Imagine turning a doorknob—it's torque that gets the door swinging.

• Torque transforms force into rotation, making it a pivotal concept to master for acing JEE Main.

Moment of Inertia: Unraveling the Resistance:

• Just as mass resists linear acceleration, the moment of inertia opposes rotational acceleration. It's like an object's reluctance to speed up its spin.

• Different shapes have unique moments of inertia. Think of it as objects expressing their preference for spinning dynamics!

Rolling on Fun:

• Wheels rolling smoothly is an everyday example of combined linear and rotational motion. Understanding the mechanics behind rolling unlocks new perspectives.

• Dive into the world of wheels, cylinders, and spheres, and see how they elegantly combine translation and rotation.

Gyroscopic Magic:

• Gyroscopes, those spinning wonders, showcase the extraordinary effects of rotational motion. They defy gravity, maintain stability, and even aid navigation!

• Imagine steering a spacecraft using the gyroscope's magical properties—sounds like something out of a sci-fi adventure, doesn't it?

Visualizing with Kinematics:

• Just as we used kinematics for linear motion, now it's time to apply it to rotations. You'll learn equations and concepts to predict the angular journey of spinning objects.

• Imagine tracing the path of a spinning top in your mind—it's kinematics that unravels its graceful dance.

Embark on this engaging voyage into the world of rotational motion. From dancers twirling to wheels rolling, from gyroscopes defying gravity to moments creating spins, every concept in this chapter unveils a captivating facet of physics. Prepare to be enthralled as you explore this dynamic domain, readying yourself for a triumphant journey through JEE Main!

Benefits of learning Rotational Motion for JEE Mains with Vedantu’s Notes 

• Vedantu’s notes break down challenging topics like torque and angular momentum into easy steps, making them simpler to grasp.

• These notes are well-organized, allowing you to quickly review all essential points without going through lengthy explanations.

• Vedantu’s notes highlight the types of rotational motion questions that commonly appear in JEE exams, helping you focus on what matters most.

• By practicing with these notes, you’ll learn how to apply formulas and solve questions efficiently, which is key for JEE.

• The notes are created by experienced teachers who understand the JEE format, ensuring you get accurate and useful information.

• With downloadable PDFs, you can study rotational motion anywhere, making it convenient to review concepts on the go.

Achieve Success Through Vedantu’s JEE Main Notes

As you aim for success in your exams, rely on Vedantu's Rotational Motion JEE Main Notes. We stand out with our special way of teaching that combines expert help and easy-to-use materials. Our detailed revision notes make tough ideas easy, making your preparation better. and guess what? You can get these helpful resources as FREE PDFs. Count on Vedantu to support you as you work towards excelling in your exams. Improve your learning, make studying easier, and achieve success with Vedantu.

Next Steps: Further Resources for JEE Main 2025 Rotational Motion

Ready to take your JEE Main 2025 Rotational Motion preparation up a notch? Delve into these crucial resources:

• Practice Papers: Hone your skills with targeted practice.

• Mock Tests: Simulate exam conditions and boost your confidence.

• Sample Papers: Familiarize yourself with the question patterns.

• Previous Year Question Papers (PYQPs): Gain insights into the exam's structure and trends.

Combine these resources to refine your understanding and exam-taking abilities. Elevate your performance for JEE Main 2025!

Here are the links for the additional resources of JEE Main 2025:

Easy Access to JEE Main Physics Notes: Chapter-wise Links for 2025

Easily enhance your JEE Main Physics preparation for 2025 with our chapter-wise notes. GetThe links from the table below:

Download Subject-wise Revision Notes for JEE Main 

Get the links to download the subject-wise JEE Main Revision Notes PDF from the table below for FREE.