Which type of acceleration does not involve changes in speed?

Angular acceleration is the correct answer because it refers to the rate of change of angular velocity over time. This type of acceleration typically involves a change in direction rather than a change in speed. In circular motion, for instance, an object can maintain a constant speed while continuously changing its direction, which is a hallmark of angular acceleration.

For example, when a car goes around a circular track at a constant speed, it is experiencing angular acceleration. Its velocity vector is changing direction, thus indicating that acceleration is present, even though the speed remains constant. This is fundamentally different from other types of acceleration, such as linear acceleration, which involves changes in the speed of an object in a straight line, or radial acceleration, which can refer to the acceleration directed toward the center of a circular path that reflects changes in both direction and speed.

Overall, the concept of angular acceleration is critical in physics and aerospace physiology, particularly when considering how an object behaves in rotational motion without necessarily speeding up or slowing down.