A bullet passes past a person at a speed of `220 m s^-1`. Find the fractional change in the frequency of the whistling sound heard by the person as the bullet crosses the person. Speed of sound in air `= 330 m s^-1`.

Explanation

Let the frequency of the bullet wil be f
given `u=330 m/s, v_s=220m/s`
a. Apparent frequency before crossing
`rarr f^1=(330/(330-220))f=3f`
b. Apparent frequency after crossing
`rarr f^11=((330-(330+220))f=0.6f`
So, `(f^11/f^1)=(0.6f)/(3f)=0.2`
therefore
FractioN/Al change `=1-0.2=0.8`