KA Passage- Using ultrasounds to measure blood flow velocity

[lightng]

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The answer to this passage doesn't make much sense to me

https://www.khanacademy.org/test-pr...-ultrasounds-to-measure-blood-flow-velocity-1


Shouldn't the received frequency be lower, resulting in a negative doppler shift since the blood is flowing AWAY from the transducer?

It's even shown in this webpage below

http://radiologykey.com/physical-principles-of-doppler-ultrasound/


By my intuition I would have thought the answer to be f0 > f'

Thoughts?

 

[wizzed101]

With theta between 0 and 90, blood is flowing toward not away from the transducer. The figure is misleading.