Hello guys, The title might be slightly misleading, it's not related to general physics. It's a hypothetical question that's far from being realistic of practical; Suppose you have a very very long bar, and suppose it's layed on a type of material with no friction, a person stands at the 1st extremity A of the bar and pushes it, how will the other extremity B react? Please note that the lenght here is theoretical (consider it like 1 AU and the bar is layed on some gigatic planet or whatever), if the action happened at A at t0, how long does it take to reach B? Does the force that pushed the bar at A have a propagation time through the bar? Or does it happen instantly? And if not, what are the parameters that determines this reaction time? (density of the bar, etc..) If this question have been answered somewhere else, please put a link so I can follow it's details. Thanks.