Question

A train is approaching a station at 90 km/h sounding a whistle of frequency 1000 Hz. What will be the apparent frequency heard
hu the listener sitting on the platform if the train moves away from the station with the same speed? (speed of sound=340 m/s)
A. 931.5 Hz
. B. 105.7 Hz
. B. 105.7 Hz
C. 1359 HZ
C. 135.9 Hz D. 153.1 Hz E. 164.9 Hz​

Answer 1

Answer:

yeah

Explanation:

b is best answer with my view and solution

Answer 2

Answer:

The apparent frequency is 931.5 Hz.

(A) is correct option.

Explanation:

Given that,

Frequency = 1000 Hz

Speed of whistle = 90 km/h

Speed of sound = 340 m/s

We need to calculate the apparent frequency heard  

Using formula of apparent frequency

$f=f_{0}(\dfrac{v+v_{o}}{v-v_{s}})$

Where, $v_{o}$ = speed of observer

If observer at rest, then the speed of observer will be zero.

$v_{s}$ = speed of source

Speed of source is negative because the train moves away from the station.

v = speed of sound

Put the value into the formula

$f=1000(\dfrac{340}{340-(-90\times\dfrac{5}{18})})$

$f=931.5\ Hz$

Hence, The apparent frequency is 931.5 Hz.