A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style onto a surface marked with lines... link 6 years, 7 months ago
you may be knowing about the formula i.e. total distance/total time = speed [DISTANCE CAN BE IN KM /M AND TIME CAN BE IN SECOND /MINUTES.}so answer is 18m/6seconds =3meters per second.
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