A radar pulse sent out to an airplane at a distance of 20.0 km will return as an echo to the source in what time interval? (c = 3.00 108 m/s)
a. 33.3 10-6 s
c. 66.7 10-6 s
b. 133 10-6 s
d. 0.0333 10-6 s
Question 2
A 500-Hz whistle is moved toward a listener at a speed of 10.0 m/s. At the same time, the listener moves at a speed of 20.0 m/s in a direction toward the whistle. What is the apparent frequency heard by the listener? (The speed of sound is 340 m/s.)
a. 473 Hz
c. 533 Hz
b. 485 Hz
d. 545 Hz
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