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CBSE Text Book:
System of particles and rotational motions – web notes
Topic Tree
Topic Tree of “System of Particles and Rotational Motion”
Chapter Overview:
- Introduction
- Motion of single particle and extended bodies
- Definition of rigid bodies
- Centre of Mass
- Definition and significance
- Centre of mass for systems of particles
- Motion of the Centre of Mass
- Relation to external forces
- Applications in translational motion
- Linear Momentum of a System of Particles
- Definition
- Conservation of linear momentum
- Vector Product of Two Vectors
- Definition
- Properties
- Applications in rotational motion
- Angular Velocity and Its Relation with Linear Velocity
- Angular displacement
- Angular velocity as a vector quantity
- Torque and Angular Momentum
- Moment of force (torque)
- Angular momentum of a particle
- Conservation of angular momentum
- Equilibrium of a Rigid Body
- Conditions for mechanical equilibrium
- Applications
- Moment of Inertia
- Definition
- Calculation for various shapes
- Physical significance
- Theorems of Perpendicular and Parallel Axes
- Derivation and application
- Kinematics of Rotational Motion About a Fixed Axis
- Angular displacement, velocity, and acceleration
- Dynamics of Rotational Motion About a Fixed Axis
- Relation between torque and angular acceleration
- Rotational analogs of Newton’s laws
- Angular Momentum in Case of Rotation About a Fixed Axis
- Definition and significance
- Applications in dynamics
- Rolling Motion
- Pure rolling and its conditions
- Kinetic energy in rolling motion
Terms and Definitions
| Term | Definition |
| System-of-Particles | A collection of particles interacting with each other and potentially subjected to external forces. |
| Centre-of-Mass | The point at which the total mass of a system of particles can be considered to be concentrated. |
| Rigid-Body | An ideal body with perfectly fixed shape and size, where the distance between any two points remains constant. |
| Linear-Momentum | A vector quantity representing the product of mass and velocity of an object (P = mv). |
| Angular-Velocity | The rate at which an object rotates about a fixed axis (ω = dθ/dt). |
| Torque | The rotational equivalent of force, representing the moment of force about an axis (τ = r × F). |
| Angular-Momentum | The rotational analog of linear momentum, defined as L = r × p. |
| Moment-of-Inertia | A scalar measure of an object’s resistance to rotational motion about an axis (I = Σmᵢrᵢ²). |
| Rotational-Kinetic-Energy | The energy possessed by a body due to its rotational motion (KE_rot = 0.5 Iω²). |
| Equilibrium-of-Rigid-Body | A state where the net force and net torque on a rigid body are zero. |
| Theorem-of-Parallel-Axes | Moment of inertia about a parallel axis is I = I_COM + Md². |
| Theorem-of-Perpendicular-Axes | For a planar object, the moment of inertia about an axis perpendicular to the plane is I_z = I_x + I_y. |
| Rolling-Motion | A combination of translational and rotational motion where v_point of contact = 0 (pure rolling). |
| Linear-Momentum | If the net external force on a system is zero, its total linear momentum remains constant. |
| Angular-Momentum | If the net external torque on a system is zero, its total angular momentum remains constant. |
| Vector-Product | A mathematical operation used to compute quantities like torque and angular momentum (a × b = |a||b|sinθ). |
| Translational-Motion | Motion in which all parts of a body move with the same velocity. |
| Rotational-Motion | Motion where different parts of a body move with different velocities, often involving rotation. |
| Pure-Rolling | Rolling motion without slipping, where the velocity of the point of contact with the surface is zero. |
| Rigid-Body-Dynamics | The study of forces and motions of rigid bodies under the influence of external forces and torques. |
Activities
Lecture-1
Lecture -2 – Angular momentum and Moment of Inertia
Lecture-3 Torque
Lecture-4 – Equation of Motion of an Object moving in an Inclined plane
Lecture-5 – Problem based on translational and rotational equilbrium
Lecture – 6 – Work done by a torque