# NEET Physics Waves Questions Solved

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A person feels 2.5% difference of frequency of a motor-car horn. If the motor-car is moving to the person and the velocity of sound is 320 m/sec, then the velocity of car will be

(1) 8 m/s (approx.)

(2) 800 m/s

(3) 7 m/s

(4) 6 m/s (approx.)

(1) By Doppler’s formula $n\text{'}=\frac{nv}{\left(v-{v}_{S}\right)}$

Since, source is moving towards the listener so $n\text{'}>n$.

If n = 100 then n' = 102.5

$102.5=\frac{100×320}{\left(320-{v}_{S}\right)}$

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