Is Length Invariant Under Galilean Transformations?

[hatachiclaud]

Homework Statement

Consider a bar of length as measured in frame S. Show that the bar has the same length in
frame S’, that is, show that lengths are invariant under Galilean transformations.

Homework Equations

x'=x-vt

The Attempt at a Solution

I know that t'=t
y'=y
z'=z
so

x'=x-vt


The problem is that i don't understant how to make it valit with the equation, i undestant that the space from th point of view of S' dilates and is not invariant .

 

[PsychonautQQ]

skip to 12:40 on this video

 

[hatachiclaud]

Yep but how i show that the leght in that equation is invariant in galilean tranformation