1. The problem statement, all variables and given/known data Hello physics friends! Here's a problem that's troubling me. This is a tank or truck with relativisti velocity V where the 2N pads are moving around the external edges of the tank. The question is, how many panels will be in contact with the ground at a given instant? And, if one of the panels leaves an imprint on the ground, what's the distance from imprint to imprint? 2. Relevant equations t=proper time* gamma Lorentz transformation Addition of velocities?? 3. The attempt at a solution Now, the driver who is sitting in the front sees that the upper panels are movin towards him at velocity v and the lower panels are moving away at v. However from the ground what is it that I observe? I see the lower panels still and the upper panels at 2V, right? I know that if the driver has a clock it has to run slower and the distance I see from the outside is shorter than the proper lenght. But I'm confused and I don't know how to continue. Thanks!!!