# NEET Questions Solved

A source of sound is travelling towards a stationary observer. The frequency of sound heard by the observer is of three times the original frequency. The velocity of sound is v m/sec. The speed of source will be

(1) $\frac{2}{3}v$

(2) v

(3) $\frac{3}{2}v$

(4) 3v

(1) ${n}^{\text{'}}=n\left(\frac{v}{v-{v}_{S}}\right)$$\frac{n\text{'}}{n}=\frac{v}{v-{v}_{S}}$

$⇒\frac{v}{v-{v}_{S}}=3⇒{v}_{s}=\frac{2v}{3}$

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