Concept explainers
The motion detector used in a physics lab sends and receives 40 kHz ultrasonic pulses. A pulse goes out, reflects off the object being measured, and returns to the detector. The lab temperature is 20°C.
a. What is the wavelength of the waves emitted by the motion detector?
b. How long does it take for a pulse that reflects off an object 2.5 m away to make a round trip?
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