A submarine A travelling at 17 ~m / s is being chased along the line of its velocity by another submarine B travelling at 34 ~m / s . B sends a sonar signal of 600 ~Hz to detect A and receives a reflected sound of frequency v. The of v is [Speed of sound in water =1500 ~ms ^ -1 ]
A. 613.7 ~Hz
Given, velocity of submarine A, v_A=17 ~m / s Velocity of submarine B, v_B=34 ~m / s Signal sent by submarine B is detected by submarine A can be shown as Freqency of the signal, f_0=600 ~Hz Speed of sound in water v_s=1500 ~ms ^ -1 Frequency received by submarine A is f_1= ( v_ S -v_A v_ S -v_B ) f_0= [ 1500-17 1500-34 ] 600 ~Hz f_1= 1483 1466 600 Frequency received by submarine B is f_2= ( v_ S +v_B v_s+v_A ) f_1 Substituting given values and f_1 value from Eq. (i), we get aligned f_2 & = ( 1500+34 1500+17 ) [ 1483 1466 600 ] \\ f_2 & =1.0112 1.0115 600 \\ f_2 & =613.7 ~Hz aligned
Related: Physics — Waves and Sound · All PYQ Banks