Clockwise

Called The terms of rotation and direction of rotation, also of circulation or circulation direction, indicate the direction in which, from a certain point of view, move points on a circle, with one between the two alternatives

  • Clockwise, clockwise or in the geodetically positive circulation or rotation ( in the mathematically negative sense )

As well as

  • Counter-clockwise, counter-clockwise or in the mathematically positive circulation or rotation ( in the negative sense geodetically )

Differs.

  • 2.1 clock
  • 2.2 Geodesy and Navigation
  • 2.3 Meteorology
  • 2.4 screw thread
  • 2.5 motor shafts
  • 2.6 rotation of the polarization plane of the light
  • 2.7 galaxies
  • 2.8 circling of shrines

Definitions

Clockwise

It is given a circular surface, which rotates about its center point and as viewed in the direction of the axis of rotation. Now describe points of the surface in the rotation a first upwards, then to the right line running, as is the direction of rotation " right", " clockwise " or " in the mathematically negative sense of rotation ".

Counterclockwise

It is given a circular surface, which rotates about its center point and as viewed in the direction of the axis of rotation. Now describe points of the surface in the rotation a first upwards, then left running line, then the direction of rotation " left", " counter-clockwise", or " in the mathematically positive sense."

Mathematical definitions regarding coordinate systems

The above information "in the mathematically positive sense " or " in the mathematically negative sense of rotation " set the so-called right-handed coordinate system commonly used (on the right in the figure) ahead.

In mathematics, there is also the so-called left-handed coordinate system (left in the figure) with opposite directions of rotation. Here, " in the mathematically positive direction " with " clockwise " identical.

In the XY two-dimensional system thus applies, regardless of whether it is right-handed or left-handed The positive direction is the one through which the positive x-axis is converted to the shortest path to the positive y-axis.

In three-dimensional xyz - system applies analogously, whether right-handed or left-handed, in both cases, the determination is that the positive direction of rotation ( about the Z -axis) that is, through which the positive x-axis by the shortest route to the positive y- axis is transferred. In rotation about the x - axis positive direction of rotation that, in turn, converted to the shortest path, the positive y- axis to the positive z-axis. In rotation about the y-axis is "positive", which leads to the shortest path through the positive Z - axis in a positive x-axis.

Memory aid

For the relationship between Rechts-/Linksdrehend and rechts-/linkshändigem coordinate system:

  • In a right-handed coordinate system to the right, that is, in the clockwise direction,
  • In a left-handed coordinate system to the left, ie in the counter-clockwise direction.

Direction of rotation and axial vector

In the representation of rotations and rotation parameters such as angles, angular velocities, accelerations, torques, impulses, etc., with the help of Axialvektoren corresponds whose orientation - clear: the direction of its arrow head - with the direction of rotation: They are found depending on the chosen coordinate system with the help of the Left - or rights - fist rule.

Examples of the application of the direction of rotation

Clock

Because the hands are veering to most watches, is reversed when right turns are meant mostly just from clockwise ( CW ) spoken. Links rotating watches, however, are very rare. In Münster ( Westphalia ), there is a left-handed astronomical clock which dates from the 16th century, when the clockwise rotation of the astronomical and (presumably dependent ) had not yet been enforced all the other watches. Presumed cause that is right-handed clock finally penetrated, is the fact that the rod - shadow horizontal sundials on the northern hemisphere of the earth, where practically took the whole development of timing devices, also always turn in that direction.

Geodesy and Navigation

In geodesy, positive rotation is equivalent to a clockwise rotation (see Cartesian coordinate system (geodesy )), where the rotation angle in the control of the north direction from be measured.

In the navigation, however, and depending on the type of vehicle and used, while still always right-handed reference system both spins clockwise as counterclockwise as positive, with land vehicles that use the ENU - system (East - North -Up ) as a reference system, is a positive rotation a counter-clockwise direction, at room, air and water vehicles including submarines, however, the further (North - East - down) to use for reasons of compatibility with the traditional compass direction of the NED system as a reference, a positive rotation, a clockwise.

How this apparent contradiction is to be explained, showing the adjacent figures: ENU - and NED - system are similar in that the xy plane of both runs parallel to the earth's surface, which is perpendicular thereto z- axis but in the case of land vehicles shows from the center of the earth away in space, air and water vehicles, however, the center of the earth towards (see also roll- pitch-yaw angle: details).

Meteorology

In meteorology (and thus also in the navigation at air and water vehicles ) is called a right-handed wind as right-handed, one left-handed wind as a back -turning.

Screw thread

A screw is provided with right-handed or right-hand thread, as it moves when rotating in a clockwise direction away from the viewer into the nut. For grinding it is rotated to the left. Screws with left-hand threads are used only for special purposes, such as turnbuckles, used to gas cylinders for flammable gases or for parts of bicycle axles.

Motor shafts

The majority of all internal combustion engines has dextrorotatory crankshafts ( cars and trucks, by definition, from the front ( fan ) to the rear ( flywheel ) looking ). In twin-engine boats / ships each have a right-handed and a left- turning motor is installed ( to compensate for the effects as centrifugal and shear forces to the propellers ). When the direction of rotation of drive machines (eg electric motors) that is specified, which can be seen when looking at the face of the driven side ( not applicable to output on both sides ). Accordingly, a drill rotates counterclockwise. Moreover, the direction of rotation is often characterized by means of an arrow ( for example, on upright and hand - grinding ).

Rotation of the polarization plane of the light

As a right - or left-handed is called an optically active substance, that is a substance that rotates the plane of polarization of polarized light in that direction. Reference direction is the direction of view opposite to the moving direction of the light. A well-known example of food chemistry, the mutually enantiomeric ( mirror image ) compounds L -( ) -lactic acid and D ( - ) lactic acid in right - or left-handed yogurt cultures.

Galaxies

In astronomy spiral galaxies are characterized among other things by its direction of rotation. The direction of rotation can be recognized by the shape and arrangement of their spiral arms. A distinction is levorotatory S-shaped galaxies of right-handed Z-shaped galaxies. Initial observations indicated out that the levorotatory galaxies would predominate numerically. However, detailed statistical studies as part of the Galaxy Zoo project could not confirm this hypothesis.

Circling of shrines

Catholic clergy to the pope circle the altar at the beginning of worship counterclockwise, as Muslims, the Kaaba and Bonpos their sanctuaries, Buddhists and Hindus on the other hand in a clockwise direction.

293988
de