A radar transmitter Z is fixed to a reference frame S' that is moving to the right with speed v relative to reference frame S (Figure). A mechanical timer (essentially a clock) in frame S', having a period 16 (measured in S'), causes transmitter T to emit timed radar pulses, which travel at the speed of light and are received by R, a receiver fixed in frame S.

(a) What is the period r of the timer as detected by observer A, who is fixed in frame S?

(b) Show that at receiver R the time interval between pulses arriving from T is not τ or τ0, but τ R = τ0 ?? c + v /c - v

(c) Explain why receiver R and same reference frame, measure observer A, who are in a different period for the transmitter.

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