Referring to the attached drawing: Two rods 3m long. Rod A is moving at 0,866 c from right to left. The pictures are taken from the point of view of rod B. ( 1 )In 1 a ray of ligth reaches the end of both rods. It happens that the reading of the clocks at rod A and rod B is 0. Because v = 0.866 *c -> l´= l * 0.5 , thats why the left end of rod A is at the middle point of rod B. ( 2 )In 2 after 10 ns ( at clocks on rod B ) the light reaches the left end of rod B, assuming c = 30 cm/ns. Rod A has moved 0.866 * c * 30 ns/cm = 260 cm. But, because t'= t *0.5, the reading on clocks at rod A is 5 ns. So the light has moved, in the frame of reference of A, 150 cm -> the light must be at the middle of rod A, and it isnt according to the explained in ( 2 ). Where is the mistake ?