Rattleback

A Celtic Wackelstein (also Celtic loose wood, Celt or Rattleback ) is a physical toy. It consists of a ten to twenty centimeters long, at the bottom of ellipsoidal shaped piece of stone, wood, plastic or other material.

Properties

If one turns one lying on the rounded side rocking stone on a flat surface so it shows depending on the direction a different behavior: In one direction of rotation (eg clockwise), the rocking stone rotates as expected stable until it comes to a stop due to friction. In the other direction, however, the Wackelstein quickly decreases, where he starts to wobble along the longitudinal axis. After the rotation is completely gone in a loose vibration, the Wackelstein begins opposite to the original direction of rotation to rotate. This direction of rotation is also called preferred direction of rotation of the loose stone.

Naming

The name Celtic Wackelstein is because supposedly Celtic priest the stones to make decisions or to influence decisions of others used.

Cause of the behavior

The cause of the movement is a little graphic. The mass of a loose stone is asymmetrically distributed, which is achieved by natural events or sunken or seated weights. The resulting imbalance and friction with the pad ensure the wobbling. During each oscillation of the rocking stone tilts slightly towards his excess weight, such that rotation takes place in his preferred direction.

There are extensive physical examinations for Wackelstein.

Chirality

A planar surface and the vertical force of gravity acting on it is rotationally symmetrical. The existence of a preferred direction of rotation of the loose body must therefore be derived inherent properties of this body. Is the Rocking Stone, a flat two-fold axis-parallel section of an elongated or ellipsoid, as in longitudinal and transverse direction applies mirror symmetry. Similar in a two -Canadian paddlers sit on Wackelstein the additional masses, the image, and turtles, diagonal, namely front and rear, while left and right side of each slightly Boat longitudinal axis. The axis of least moment of inertia is therefore differ from the longitudinal axis of the boat form clearly in the direction of the diagonal of this additional masses. Higher - otherwise the boat would tip over - is the longitudinal axis of the ellipsoid, which now spans a helix with the axis of minimum moment of inertia.

These two axes are relevant movement by tilting vibration and bearing forces, relate to each other clearly chiral location - because the projection of a the other crosses at an angle away from 90 °. This chirality makes chiral behavior of loose stone plausible.