Rotational Dynamics Notes

Rotational Dynamics – Class 12 NEB Physics (2082/2083 Syllabus) The chapter “Rotational Dynamics” explains the motion of rigid bodies around a fixed axis. It connects linear motion with rotational motion and includes concepts like torque, moment of inertia, angular momentum, and rolling motion. This chapter is important for NEB board exams and entrance tests. Main Topics Covered: Rotational motion and angular quantities Relation between linear and angular motion Torque and its relation with angular acceleration Moment of inertia (MI) – definition and formula Radius of gyration Theorems of MI – parallel axis and perpendicular axis Angular momentum and its conservation Kinetic energy of rotation Rolling motion – pure rolling on a horizontal surface Comparison between translational and rotational motion Numerical problems based on real exams Important Formulas: Angular displacement (θ), velocity (ω), acceleration (α) Linear and angular relation: v = rω, a = rα Torque (τ) = I × α Moment of inertia (I) = Σmr² Angular momentum (L) = Iω Rotational kinetic energy = ½ Iω² Rolling motion total KE = ½ mv² + ½ Iω² Parallel axis theorem: I = I_cm + Md² Perpendicular axis theorem: Iz = Ix + Iy Why Use These Notes: Aligned with NEB Class 12 Physics syllabus (2082/2083) All concepts explained with examples Includes derivations, formulas, and numericals Great for NEB board exam preparation Helpful for engineering and science entrance exams