One historic Jewish clock was built that way in the Jewish Town Hall in Prague in the 18th century, using right-to-left reading in the Hebrew language. Occasionally, clocks whose hands revolve counterclockwise are sold as a novelty. The best-known surviving example is the Münster astronomical clock, whose hands move counterclockwise. Some clocks were constructed to mimic this. This effect is caused by the plane of the dial having been rotated through the plane of the motion of the sun and thus the shadow is observed from the other side of the dial's plane and is observed as moving in the opposite direction. For a vertical sundial (such as those placed on the walls of buildings, the dial being below the post), the movement of the sun is from right to top to left, and, accordingly, the shadow moves from left to down to right, i.e., counterclockwise. 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. 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). 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. Clocks with hands were first built in the Northern Hemisphere (see Clock), and they were made to work like horizontal sundials. The shadow of a horizontal sundial in the Northern Hemisphere rotates clockwiseĬlocks traditionally follow this sense of rotation because of the clock's predecessor: the sundial. 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"). The terms clockwise and counterclockwise can only be applied to a rotational motion once a side of the rotational plane is specified, from which the rotation is observed. " Widdershins" or "withershins" (from Middle Low German "weddersinnes", "opposite course") was used for counterclockwise. Terminology Viewed from the north, Earth rotates anticlockwise or counterclockwiseīefore clocks were commonplace, the terms " sunwise" and "deasil", "deiseil" and even "deocil" from the Scottish Gaelic language and from the same root as the Latin "dexter" ("right") were used for clockwise. Three-dimensional rotation can have similarly defined senses when considering the corresponding angular velocity vector. The opposite sense of rotation or revolution is (in Commonwealth English) anticlockwise ( ACW) or (in North American English) counterclockwise ( CCW). Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands relative to the observer: from the top to the right, then down and then to the left, and back up to the top. Two-dimensional rotation can occur in two possible directions or senses of rotation. Trending Questions How many leads or pins are there on a 7-segment display which contains decimal point? Is 106 degrees angels acute obtuse.The counterclockwise or anticlockwise direction
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