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.

Options

A. the wavelength of sound reaching the hill is `v/f`
B. the wavelength of sound reaching the hill is `(v-v_c)/f`
C. The wavelength of sound of horn directly reaching the observer is `(v+v_c)/f`
D. the best frequency observed by the observer is `(2v_x(v+v_@)f)/(v^2-v_c^2)`

Explanation

To solve the problem, we need to analyze the situation step by step using the Doppler effect for sound. Let's break it down:

### Step 1: Understand the scenario
A car is moving towards a hill with speed \( v_c \) and blows a horn of frequency \( f \). An observer is following the car with speed \( v_0 \). The speed of sound in air is \( v \).

### Step 2: Frequency heard by the hill
When the car blows the horn, the frequency \( f_1 \) that the hill receives can be calculated using the Doppler effect formula for a moving source and a stationary observer (the hill acts as a stationary observer):

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