A rod whose length at rest is 10 meters is moving to the right along the positive x-axis of the O-frame with velocity V = 0.70c. An observer riding on the rod (i.e. in the O'-frame) sets off two explosions simultaneously - so he says. If the rod is parallel to the x-axis how far apart are the two explosions (in meters) in the O-frame? I found the length the rod appears in the O-frame (about 7.1m) but am not really sure how to answer the question if I am not given how far in meters apart the explosions happen in the O'-frame. Can someone explain? thanks.