let there be given a stationary rigid rod; and let its length be l as measured by a measuring-rod which is also stationary. we now imagine the axis of the rod lying along the axis of x of a stationary system of co-ordinates, and that a uniform motion of parallel translation with velocity v along the axis of x in the direction of increasing x is then imparted to the rod. we now inquire as to the length of the moving rod, and imagine its length to be ascertained by the following operation:(adsbygoogle = window.adsbygoogle || []).push({});

by means of stationary clocks set up in the stationary system and synchronizing, an observer ascertains at what points of the stationary system the two ends of the rod to be measured are located at a definite time. the distance between these two points, measured by the measuring-rod, is a length which may be designated "the length of the rod".

how does the observer ascertains the points of the stationary system at which the two ends of the rod to be measured are located at a definite time?

i do not know how to ascertain the two points on the axis of x in order to measure the distance between them.

need help

thanks

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# On the Relativity of Lengths and Times

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