This calculator works out the g-force experienced in circular motion, from the speed and the radius of the turn, expressing the acceleration as a multiple of normal gravity. G-force is the way we describe acceleration relative to the pull of gravity at the Earth's surface, where one g is the familiar acceleration we feel standing still. When an object moves in a circle, it constantly accelerates toward the centre, and that centripetal acceleration, divided by gravity, gives the g-force felt. This is why tight, fast turns press you into your seat, why fighter pilots and racing drivers train to withstand high g, and why fairground rides are designed around the g-forces they produce. The faster you go and the tighter the turn, the higher the g-force. This calculator computes it. You enter the speed and the radius of the circular path, and the calculator returns the g-force as a multiple of gravity, the underlying centripetal acceleration in metres per second squared, and the speed and radius for reference. The results update as you type. Use it for physics study, for understanding cornering and rides, or for motorsport and aviation interest. The centripetal acceleration is the speed squared divided by the radius, and the g-force is that acceleration divided by 9.81, the acceleration due to gravity. Because the acceleration depends on the square of the speed, doubling your speed quadruples the g-force for the same radius, which is why high-speed cornering produces such strong forces. A tighter radius also raises the g-force, since the direction must change more sharply. For context, a brisk road corner might be a fraction of a g, a rollercoaster loop several g, and sustained forces above about five g become hard for people to tolerate. This calculator gives the centripetal g-force; the total felt also combines with gravity depending on orientation.
Centripetal acceleration = speed² / radius; g-force = acceleration / 9.81. Doubling speed quadruples the g-force. This is the centripetal g-force, separate from gravity's direction.
The centripetal acceleration of circular motion is the speed squared divided by the radius of the turn. Dividing that acceleration by 9.81, the acceleration due to gravity, expresses it as a g-force, a multiple of normal gravity. A higher speed or tighter radius increases the acceleration and so the g-force.
Travelling at 20 metres per second around a circle of radius 50 metres, the centripetal acceleration is 20 squared divided by 50, which is 400 over 50, equalling 8 metres per second squared. Dividing by 9.81 gives about 0.815 g, so you would feel about four-fifths of normal gravity pressing you toward the outside of the turn.
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