Question

A car moves towards a hill with speed $v_C.$ It blows a horn of frequency $f$ which is heard by an observer following the car with speed $v_0.$ The speed of sound in air is $v$.

• A. The wavelength of sound reaching the hill is $\frac{v}{f}$
• B. The wavelength of sound reaching the hill is $\frac{v-v_c}{f}$
• C. The beat frequency observed by the observer is $\left(\frac{v+v_{\circ }}{{v-v}_c}\right)f$
• D. The beat frequency observed by the observer is $\frac{2v_c\left({v+v}_o\right)f}{v^2-v^2}$

Answer 1

Answer: (B), (D)

The correct options are
B The wavelength of sound reaching the hill is $\frac{v-v_c}{f}$
D The beat frequency observed by the observer is $\frac{2v_c\left({v+v}_o\right)f}{v^2-v^2}$