Angular acceleration refers to the change in the angular velocity of an object as a result of torque applied about its center of mass. If a force is applied at a fixed point on a rotating object, it generates angular acceleration without affecting the center of mass if the mass is fixed. However, if the mass is not fixed, both rotational and translational movements occur, resulting in different tangential velocities for various points on the object. The tangential acceleration varies with distance from the axis of rotation, with points further from the center experiencing greater tangential acceleration. Understanding these concepts is crucial for analyzing rotational dynamics accurately.