A car approaching a crossing at a speed of 20 m/s sounds a horn of frequency 500Hz. when at 80m from the crossing, Speed of sound in air is 330 m/s. What freqnency is heard by an observer 60 m from the crossing on the straight road which crosses car road at right angles?

Explanation

The situation is as shown in figure. `cos theta=(80)/(100)=(4)/(5)`

`f_(app)=((V)/(V-Vcos theta))f=((330)/(330-20xx(4)/(5)))(500)`
`=525.5Hz`