A sigle wave Superposition of waves © The scientific sentence.
2010 1. Moving source forward an observer at rest The source S
is moving at right at the speed Vs in the frame of the observer
at rest. At the precise time T, which is the period of the wave;
this wave that was emitted from So reaches the observer. The
source at this time is not located at the position So, that is
at the distance Ls, but It was moved and now It is located at
the distance L's. For the observer, It appears that the wave was
originated from the position S taking T' as time to arrive at
its position. If Vwis the speed of the wave, we can write: L's =
Vw. T' Ls = Vw. T L's = Ls + Vs. T Vw. T '= Vw. T +Vs. T T' = T
. (Vw+ Vs)/Vw With ƒ = 1/T, we have: ƒ' = ƒ[Vw/(Vw+ Vs)] ƒobs =
ƒ . Vw/(Vw+ Vs) Where ƒ' is the apparent frequency for the
Observer, and ƒ is the real frequency of the wave. If the source
is stationary (Vs = 0), then ƒ' = ƒ' and T' = T, that is the
observer gets waves at every real period. 2. Moving source
toward an observer