Q 11-14-023NEETJEE MainMedium
A source of frequency $500$ Hz moves towards a stationary observer at $30$ m/s. If the speed of sound is $330$ m/s, the frequency heard is
Answer: (C) $550$ Hz
Concept. Source moving towards a stationary observer: $f' = f\dfrac{v}{v - v_s}$.
Step 1. Substitute.
$$f' = 500 \times \frac{330}{300} = 550\ \text{Hz}$$
Answer. $550$ Hz (Option C).
Solution by Sreeraj P, M.Sc Physics