Ultrasound is utilized in measuring blood flow non invasively using a phenomenon referred to as Doppler effect. (a) derive the expression of the Doppler shift.
Ultrasound is utilized in measuring blood flow non invasively using a phenomenon referred to as Doppler effect. (a) derive the expression of the Doppler shift.
(b) a horseshoe bat flies towards a moth at Vb= 9m/s, while the moth flies towards the bat at Vm =8m/s. The bat emits ultrasonic waves of frequency fbe that reflect from the moth back to the bat with frequency fbd. The bat adjusts the emitted fbe so that fbd =83 kHz, its optimal hearing frequency. (a) find the frequency fm heard and reflected by the moth. (b) calculate the frequency fbe emitted by the bat.
In several cases, a nearby star has been found to have a large planet orbiting about it, although the planet could not be seen. Using the ideas of a system rotating about its center of mass and of the Doppler shift for light ( which is in several ways similar to the Doppler effect for sound), explain how an astronomer could determine the presence of the invisible planet.
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