Positive and negative G-forces refer to the direction in which the force is experienced with respect to an object or person.
Positive G-force, often denoted as "+Gz," is experienced when the force is directed towards the head-to-toe axis, pushing the individual or object in the same direction as the force of gravity. It is commonly encountered during upward acceleration or when subjected to forces like rapid takeoff in an aircraft, roller coaster loops, or during high-speed driving. Positive G-forces push the body or object in the direction opposite to the force of gravity, causing compression on the body.
On the other hand, negative G-force, often denoted as "-Gz," is experienced when the force is directed in the opposite direction of the head-to-toe axis, pulling the individual or object away from the force of gravity. Negative G-forces are typically encountered during downward acceleration or in situations where there is a sudden decrease in speed or a rapid deceleration. Examples include freefalling in a skydive or during the "crest" of a roller coaster hill. Negative G-forces pull the body or object away from the direction of gravity, causing a sensation of weightlessness or "floating" and can lead to feelings of discomfort or strain on the body.
It's important to note that the human body can tolerate both positive and negative G-forces within certain limits. Pilots, astronauts, and individuals who engage in activities with high G-forces often undergo specialized training to handle these forces and minimize their potential negative effects on the body.