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## Homework Statement

Stan is at rest on the Earth while Mary is moving away from the Earth at a constant speed

of 0.600c. Stan and Mary start their timers when Mary passes Stan (in other words, t = t' = x = x' = 0 at that instant).

(a) When Mary has traveled a distance of 0.900 *10

^{8}m according to Stan, what is the time according to Stan?

(b) At the instant Stan reads the time calculated in part (a), what does Mary’s timer read?

## Homework Equations

Lorentz Transformation

## The Attempt at a Solution

(a) is simple. I got it correctly. t=x/V=0.5s

I got (b) wrong. I plugged in the Lorentz Transformation:

x=0

γ=1.25

V=0.600c

t=0.5s

t' =γ (t-Vx/c2) = 0.625 s.

But the answer is 0.4s, which claims that x=0.900 *10

^{8}m, not 0.

However, at the instant Stan reads the time 0.5s from his clock, he and his clock are sitting on the earth, not 0.900 *10

^{8}m away from earth. So I do not think that x=0.