Respuesta :
(a) The frequency observed by the passenger on the east-bound train when they are 1000 m apart is 675.5 Hz.
(b) After 10 seconds, the frequency observed by the passenger on the east-bound train will be greater than the frequency observed when they are 1000 m apart.
Observed frequency
The frequency observed by the passenger on east-bound train is calculated by applying Doppler shift formula.
[tex]f = f_0(\frac{v \pm v_0}{v\pm v_s} )[/tex]
where;
- f is observed frequency
- f₀ is original frequency or source frequency
- v is speed of sound
- v₀ is speed of observer (positive when moving towards source)
- vs is source frequency (negative when moving towards observer)
when the two trains are 1000 m apart
[tex]f = 600(\frac{343 +15}{343-25} )\\\\f = 675.5 \ Hz[/tex]
The frequency observed by the passenger increases with decrease in distance between the two trains.
Thus, after 10 seconds, the frequency observed by the passenger on the east-bound train will be greater than the frequency observed when they are 1000 m apart.
Learn more about Doppler shift here: https://brainly.com/question/23841569
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