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`.

Answer

8

Explanation

Let the frequency of the bullet be f.
Given: `u=300m//s,V_(s)=220m//s`
(a) Apparent frequency before crossing
`f^(1)=((330)/(330-220))=f=3f`
(b) Apparent frequency after crossing
`f^(11)=((330)/(330+220))=f=0.6f`
`((f^(11))/(f^(1)))=(0.6f)/(3f)=0.2`
therefore fractional change=1-0.2=0.8