Final answer:
The question relates to calculating the angle of departure in a unity feedback system but with the given transfer function and without further context it's not possible to provide a precise answer. The concepts of angular frequency, angular velocity, and angular acceleration are relevant to this type of question.
Step-by-step explanation:
The student is asking about the angle of departure for a unity feedback system with a given open-loop transfer function, HG(s) = K/s(s² +4s+4.5). To calculate the angle of departure, we'd typically use root locus techniques, looking at the poles and zeros of the transfer function. However, neither the full transfer function to determine the angle is provided, nor is the context for calculating it. Therefore, without additional context or information about the poles of the system, we cannot provide a precise answer.
What we can understand from the provided information is that the topic touches on concepts of angular frequency, angular velocity, and angular acceleration as they apply to rotational motion in physics. The formulas for these, as given in the question guidance, can be quite useful in different engineering and physics scenarios. For a closed-loop control system, such as the one specified in the question, these values can inform the stability and response behavior of the system.