What are the three types of G forces?

The three types of G forces generally recognized in aerospace physiology are positive G, negative G, and neutral G. Positive G forces occur when the force exerted by acceleration acts in the direction of the feet to the head, often experienced during rapid acceleration or climbing maneuvers. Negative G forces are the opposite, where the force acts from the head to the feet, frequently experienced during rapid descents or inverted flight, which can lead to various physiological effects including the pooling of blood away from the brain. Neutral G forces refer to a state of weightlessness where the body experiences no net G force, such as in free fall.

In the context of the other provided options, they contain terms that do not accurately categorize G forces in the standard way recognized in aerospace physiology. For instance, terms like "radial," "diagonal," and "angular" do not directly pertain to the classification of G forces and may refer to other aspects of physics or motion. Therefore, the classification as positive, negative, and neutral aligns with the established understanding of G forces in aerospace contexts.