Question

a red blood cell travels at a speed of 40 cm/s in a large artery. a sound with a frequency of 100 kHz enters a blood opposite the direction flow. calculate the frequency of sound reflected from the cell and detected by a receiver. (v = 1500 m/s)

Answer 1

deltaf/f = 2*v'/v
deltaf is the shift in frequency
v' is the cell velocity = 0.4 m/s
v is the sound velocity in blood = 1500 m/s
f = 100 kHz.
deltaf = 2(0.4/1500)*100 kHz = 0.053 kHz
The received frequency is 1500.053 kHz

Answer 2

(1500+0.4)/(1500-0.4)]*(100000)