- #1

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## Homework Statement

Two spaceships approach each other, each moving with

the same speed as measured by an observer on the

Earth. If their relative speed is 0.70c, what is the speed of

each spaceship?

My current understanding of the problem.

S= wrt observer on Earth

S'=wrt one of the spaceships

u= ??

u'=speed of spaceship B if S' is wrt spaceship A.

v = speed of S' wrt S (how does v fit into this problem?)

## Homework Equations

I'm great with the equations and algebra of Lorentz transformations, I'm just having trouble understanding/visualizing what the question is asking and assigning variables to knowns and unknowns.

u' = u-v / (1-uv/c

^{2})

## The Attempt at a Solution

I'd appreciate it if someone could reword the problem or answer me:

What does "their relative speed" mean? Is that their speed in S (wrt Earth) or relative to eachother? Also, when "what is the speed of each spaceship" is asked, do they mean the speed of each spaceship relative to Earth or relative to eachother? Lastly, are "with respect to" and "relative to" interchangeable terms?

Thanks a bunch