When some vehicle moves towards a stationary person, he finds difference in the frequency of horn by 2.5% of original frequency. If speed of sound is 320 m/s then, find speed of this vehicle.

When some vehicle moves towards a stationary person, he finds differen

1.	When some vehicle moves towards a stationary person, he finds difference in the frequency of horn by 2.5% of original frequency. If speed of sound is 320 m/s then, find speed of this vehicle.
Answer» `8m//s` `800 m//s` `7m//s` `80m//s` Solution : We have, `(f _(L))/( V + v _(L)) = (f _(S))/( v + v _(S))` Here if `f _(S) = 100 Hz,` then `f _(L) = 102.5 Hz` `THEREFORE ( 102.5)/(320+0) = (100)/(320 -v _(S))` `therefore 320 -v _(S) = (32000)/(102.5)` `therefore 320 - (32000)/(102.5) =v _(S)` `therefore v _(S) = ((320 xx 102.5) - 32000)/(102.5)` `v _(S) = (800)/( 102.5) = 7.8 (m)/(s) ~~ 8 (m)/(s)`