Here's a weird question where I don't quite know if length contraction or time dilation play a role. Say I have 2 spaceships moving towards each other. rest length of spaceship A is La and spaceship B is Lb. The pilot in A determines that time taken for the spaceship B to traverse the length of A is T,. What is the relative velocity B wrt A? Also, according to nose of B, what's the time taken to traverse the length of A? The way i see it, in the frame of reference of A, the pilot A is at rest, hence relative vel, is La/Tx. Does time dilation play any role at all here? Also, the second part is just Tx/gamma, right? where gamma can be find once we find the relative vel from part 1 Does this make sense?