A person observes two moving trains, 'A' reaching the station and ' B ' leaving the station with equal speed of 30 m / s. If both trains emit sounds with frequency 300 Hz, (Speed of sound: 330 m / s ) approximate difference of frequencies heard by the person will be:

Question

A person observes two moving trains, 'A' reaching the station and ' B ' leaving the station with equal speed of 30 m / s. If both trains emit sounds with frequency 300 Hz, (Speed of sound: 330 m / s ) approximate difference of frequencies heard by the person will be: (A) 33 Hz (B) 80 Hz (C) 10 Hz (D) 55 Hz

Tardigrade Admin · Accepted Answer

f 1=300((330-0/330-(-30)))=275 f 2=300((330-0/330-(30)))=330 Δ f =330-275=55 Hz

Q. A person observes two moving trains, ' $A$ ' reaching the station and ' $B$ ' leaving the station with equal speed of $30 m / s$ . If both trains emit sounds with frequency $300 Hz$ , (Speed of sound: $330 m / s$ ) approximate difference of frequencies heard by the person will be:

$33 Hz$

$80 Hz$

$10 Hz$

$55 Hz$

$f_{1} = 300 (\frac{330 - 0}{330 - ( - 30 )}) = 275$
$f_{2} = 300 (\frac{330 - 0}{330 - ( 30 )}) = 330$
$Δ f = 330 - 275 = 55 Hz$

Q. A person observes two moving trains, 'A' reaching the station and ' B ' leaving the station with equal speed of 30m/s. If both trains emit sounds with frequency 300Hz, (Speed of sound: 330m/s ) approximate difference of frequencies heard by the person will be:

33Hz

80Hz

10Hz

55Hz