Question

A sound source is falling under gravity. At some time t = 0 the detector lies vertically below source at a height H as shown in Fig. If v is velocity of sound and f₀ is frequency of the source then the apparent frequency recorded after t = 2 second is –

• A. f₀
• B. f₀$\frac{(v + 2g)}{v}$
• C. f₀$\frac{(v + 2g)}{v}$
• D. f₀$\left( \frac{v}{v–2g} \right)$

Answer 1

Answer: (D)

f₀$\left( \frac{v}{v–2g} \right)$

Answer 2

v_s = 0 + g.2 = 2g

n' = f₀ $\frac { v } { v - v _ { s } }$ = f₀ $\left( \frac { v } { v - 2 g } \right)$