Angular Impulse Theorem — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Angular Impulse Theorem This theorem applies to a rigid body or system where the net external torque is the only factor changing the angular momentum. Define angular momentum as L = r p , where p is linear momentum. Take the time derivative of L : d L dt = d dt ( r p ) . Using the product rule for cross products and considering external forces, the rate of change is shown to be equal to the net external torque. For an isolated system, the net torque is solely due to external torques: net = ext . Torques must be calculated relative to a fixed point (origin). Internal torques (e.g., forces between particles) cancel out. The system must be treated as a rigid body or a system of particles. Confusing angular momentum ( L ) with angular velocity ( ). Assuming that if the net torque is zero, the angular momentum must be zero (it only means L is constant). Forgetting that torque is a vector quantity and must be calculated using the cross product.