A stationary source sends forth monochromatic sound. A wall approaches it with velocity 33 cm/s. The propagation velocity of sound in the medium is `c=330(m)/(s)`. How much, in per cent , does the wavelength of sound change on reflection from the wall?

Explanation

To solve the problem of how much the wavelength of sound changes upon reflection from a wall that is approaching a stationary source, we can follow these steps:

### Step 1: Understand the Problem
We have a stationary sound source emitting sound waves. A wall is approaching the source with a velocity \( v_0 = 33 \, \text{cm/s} = 0.33 \, \text{m/s} \). The speed of sound in the medium is \( c = 330 \, \text{m/s} \). We need to find the percentage change in wavelength after the sound reflects off the wall.

### Step 2: Calculate the Frequency Received by the Wall
Since the wall is approaching the stationary source, it will behave as an observer receiving the sound waves. The frequency \( f' \) received by the wall can be calculated using the formula:
\[
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