While this was theorized to result from dominant brain hemispheres, 4 research shows little correlation and instead attributes it to muscle mechanics. 5.Please help to improve this article by introducing more precise citations.
March 2019 ) ( Learn how and when to remove this template message ). Clockwise motion (abbreviated CW ) proceeds in the same direction as a clock s hands: from the top to the right, then down and then to the left, and back up to the top. The opposite sense of rotation or revolution is (in Commonwealth English ) anticlockwise ( ACW ) or (in North American English ) counterclockwise ( CCW ). Widdershins or withershins (from Middle Low German weddersinnes, opposite course) was used for counterclockwise. For example, the daily rotation of the Earth is clockwise when viewed from above the South Pole, and counterclockwise when viewed from above the North Pole (considering above a point to be defined as farther away from the center of earth and on the same ray). Clocks with hands were first built in the Northern Hemisphere (see Clock ), and they were made to work like horizontal sundials. In order for such a sundial to work north of the equator during spring and summer, and north of the Tropic of Cancer the whole year, the noon-mark of the dial must be placed northward of the pole casting the shadow. Then, when the Sun moves in the sky (from east to south to west), the shadow, which is cast on the sundial in the opposite direction, moves with the same sense of rotation (from west to north to east). This is why hours must be drawn in horizontal sundials in that manner, and why modern clocks have their numbers set in the same way, and their hands moving accordingly. ![]() ![]() The best-known surviving example is the astronomical clock in the Mnster Cathedral, whose hands move counterclockwise. Historically, some Jewish clocks were built that way, for example in some synagogue towers in Europe such as the Jewish Town Hall in Prague, to accord with right-to-left reading in the Hebrew language. Almost all threaded objects obey this rule except for a few left-handed exceptions described below. A thread might need to be left-handed to prevent operational stresses from loosening it. For example, some older cars and trucks had right-handed lug nuts on the right wheels and left-handed lug nuts on the left wheels, so that, as the vehicle moved forward, the lug nuts tended to tighten rather than loosen. For bicycle pedals, the one on the left must be reverse-threaded to prevent it unscrewing during use. Similarly, the flyer whorl of a spinning wheel uses a left-hand thread to keep it from loosening. A turnbuckle has right-handed threads on one end and left-handed threads on the other. Some gas fittings are left-handed to prevent disastrous misconnections: oxygen fittings are right-handed, but acetylene, propane, and other flammable gases are unmistakably distinguished by left-handed fittings. However, in navigation, compass headings increase clockwise around the compass face, starting with 0 at the top of the compass (the northerly direction), with 90 to the right (east). An alternative formulation with sin and cos swapped gives a clockwise trace from the upper-most point. Traditionally (and still continued for the most part) turns pass counterclockwise in many Asian countries. ![]() Curiously, unlike with games, there is usually no objection when the activity uncharacteristically begins in a counterclockwise motion. While this was theorized to result from dominant brain hemispheres, 4 research shows little correlation and instead attributes it to muscle mechanics.
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