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Doc Al
Aug15-10, 08:09 AM
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Quote Quote by James S Saint View Post
No it is according to US.
Who is "US"? You? Your brother? The ground? All three frames will measure different distances and times.

You say "US", but you are actually using ground frame measurements.
We measure 2Ls of distance. In merely 1.333 secs, we measure NO distance between us. How is that not 1.5c?
It is 1.5c, but only in the ground frame. You used distances and times in the ground frame, so the closing speed is in the ground frame.