Kiertokulmaa

Kiertokulmaa is a Finnish term used in geometry, physics, and engineering to denote the rotation angle of an object or reference frame. It represents the measure of how far the orientation has changed around a fixed axis or point, from an initial orientation to a final one.

In two dimensions, kiertokulmaa is typically described as a signed angle, with positive values indicating counterclockwise rotation and negative values indicating clockwise rotation. The magnitude is measured in radians or degrees; 2π radians or 360 degrees correspond to a full turn. In three dimensions, kiertokulmaa generalizes to the angle of rotation about a specific axis, often represented by an axis–angle pair, a rotation matrix, or a quaternion.

Calculating kiertokulmaa involves comparing orientations: if a vector r(t) has an orientation θ(t) around the origin, kiertokulmaa at time t is θ(t) relative to a chosen reference orientation θ0. For sequential changes, angular displacement is the difference θ(t2) − θ(t1). The concept is distinct from angular velocity and angular acceleration, though related, as it describes the current amount of rotation rather than the rate of rotation.

Common applications include robotics, computer graphics, navigation, and the study of rigid-body dynamics, where kiertokulmaa helps describe how objects rotate over time. The term is part of Finnish technical vocabulary, and in English texts the equivalent term is usually “rotation angle” or “angular displacement.”