Waves And Sound Question 5
Question 5 - 29 January - Shift 1
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 :
(1) $33 Hz$
(2) $55 Hz$
(3) $80 Hz$
(4) $10 Hz$
Show Answer
Answer: (2)
Solution:
Formula: Doppler Effect for Sound
$f_1=300(\frac{330-0}{330-(-30)})=275$
$f_2=300(\frac{330-0}{330-(30)})=330$
$\Delta f=330-275=55 Hz$.
