Helikiiruse

Helikiiruse is a term used to describe the instantaneous speed of a point that moves along a helical path around an axis. The word combines helix with speed and is often used in physics and engineering to analyze motions that couple rotation around an axis with translation along that axis.

Mathematically, consider a particle at radius r from the axis, rotating with angular velocity ω and advancing along the axis with velocity vz. The tangential speed around the axis is vθ = ωr, and the axial speed is vz. The helikiiruse (the magnitude of the velocity vector) is v = sqrt((ωr)² + vz²). The helix angle α, which is the angle between the tangent to the helix and a plane perpendicular to the axis, satisfies tan α = vz/(ωr). The pitch, the axial advance per complete turn, is p = vz · (2π/ω) = 2π vz/ω.

Applications and context include systems with combined rotational and translational motion. In mechanical design, the concept helps describe screw mechanisms and augers, where axial advancement per turn is a key parameter. In structural biology and chemistry, helical structures such as DNA strands exhibit analogous motion along a helical path. The idea also appears in the study of helical springs and in the geometry of helical antennas, where the path length and helix geometry influence performance.

See also: helix, angular velocity, pitch, screw thread, helical gear, helical antenna.