I was doing a problem on relativity and I was thinking about the problem in terms of the postulates of Special Relativity. Special Relativity only considers motion in inertial reference frames and I was doing this problem over here;
Essentially, if I have a rod which is tilted at an angle (theta)0, with respect to the x-axis, and moving along the x-axis at speed v, and if that rod has a length L0 observed from its frame of reference, what is the length of the rod as observed by an observer in a stationary frame with respect to the frame of the rod. Also, what is the angle, as observed by that stationary observer, of the rod from the x-axis?
The problem that I with this is that the angle itself changes, which makes me think that rotation has occurred while observing the rod from one frame to the next. And if the rod itself is the second reference frame, in that case, would it not be a rotating reference frame and therefore, not within the realm of special relativity? I mean, if it is a rotating reference frame as observed from other reference frames, then it's going to have an acceleration no?
Sorry if this is a stupid question, I'm just really confused and, yet, excited about this cos it's so interesting.