A bus driving along at 39.6 kmph is approaching a person who is standing at the bus stop, while honking repeatedly at an interval of 30 seconds. If the speed of the sound is 330 m/s, at what interval will the person hear the horn ?

Options

A. 31 seconds
B. 29 seconds
C. 30 seconds
D. The interval will depend on the distance of the bus from the passenger

Answer

B

Explanation

`v=39.6km//hr=11m//s,`
`t_(1)=(d)/(330)andt_(2)=(d-11xx30)/(330)`
Now `Deltat=t_(1)-t_(2)=1`
now `t_(1)|=30sec therefore t_(2)=29sec`