A train approaching a hill at a speed of 40 ~km / hr sounds a whistle of frequency 580 Hz . When it is at a distance of 1 km from a hill, a wind with a speed of 40 ~km / hr is blowing in the direction of motion of the train find the frequency of the whistle as heard by an observer on the hill. the distance from the hill at which the echo from the hill is heard by the driver and its frequency. (Velocity of sound in ai

Step-by-step solution

aligned f^ & = ( v+ v+ -v_s ) f & = ( 1200+40 1200+40-40 ) 580 & 599 ~Hz aligned For echo to be heard by the driver, the source is to be considered at the hill having frequency 599 Hz . f ^ = ( 1200-40+40 1200-40 ) 599 t ₁( wave to reach the hill )= 1 1200+40 = 1 1240 hr . s in the above duration train moves = 40 1240 = 1 31 ~km . Now the distance between train and hill =1- 1 31 = 30 31 ~km After this instant echo will be heard 40 t +(1200-40) t =30 / 31 t = 1 1240 hrs The distance travelled by the train in this ti