In the figure below, a French submarine and a U.S. submarine move toward each ot
ID: 1962821 • Letter: I
Question
In the figure below, a French submarine and a U.S. submarine move toward each other during maneuvers in motionless water in the North Atlantic. The French sub moves at speed vF = 41.50 km/h, and the U.S. sub at vUS = 70.00 km/h. The French sub sends out a sonar signal (sound wave in water) at 2.000 103 Hz. Sonar waves travel at 5470 km/h.
(a) What is the signal's frequency as detected by the U.S. sub? Write your answer with four significant figures.
(b) What frequency is detected by the French sub in the signal reflected back to it by the U.S. sub? Write your answer with four significant figures.
Please show your work.
Please calculate a final answer.
Explanation / Answer
This is a doppler problem! frequency detected by US sub is found by using the doppler equation for moving source and listener. It looks like this freq detected = freq emitted (v + speed of listener) / (v - speed of source) where v is the speed of sound. So... freq detected by US sub = 2000 * (5470 +70) / (5470 - 41.5) = = 2041 Hz (b) Now do the same thing but the french sub is the listener, the US sub is source and the emitted freq is 2041: freq deteced by french sub = 2041 * (5470 + 41.5)/(5470 - 70) = = 2083 Hz