Sonar is used to determine the speed of an object.A 40.0-kHz signal is sent out,and a 42.0-kHz signal is returned.If the speed of sound is 345 m/s,how fast is the object moving?
A)6.9 m/s
B)8.4 m/s
C)331 m/s
D)347 m/s

Question

Quizplus · Accepted Answer

We can use the equation:
speed of object = (frequency of transmitted signal - frequency of received signal) x speed of sound / (2 x frequency of transmitted signal)
Plugging in the given values, we get: 
speed of object = (42,000 - 40,000) x 345 / (2 x 40,000) = 8.4 m/s

Sonar Is Used to Determine the Speed of an Object