To calculate the translational angular momentum of a rolling disc or sphere, the formula used is L = Iω, where L is angular momentum, I is the moment of inertia, and ω is the angular velocity. The moment of inertia varies depending on the geometric shape of the object. For rotational dynamics, fundamental relationships can be substituted, such as mass for moment of inertia and force for torque. This allows for a straightforward application of linear dynamics principles to rotational scenarios. Understanding these substitutions is crucial for solving problems in angular dynamics effectively.