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**1. Homework Statement**

Ultrasound reflected from an oncoming bloodstream that is moving at 28.7 cm/s is mixed with the original frequency of 2.41 MHz to produce beats. Use the speed of sound in human tissue as 1540 m/s. Assume that the frequency of 2.41 MHz is accurate to seven significant figures. (Hint: compare to Example 17.8 in OpenStax

*College Physics*.)

a) What frequency does the blood receive? (Give an answer in MHz, to 7 significant figures.)

b) What frequency returns to the source? (Give an answer in MHz, to 7 significant figures.)

c) What beat frequency is produced if the source and returning frequencies are mixed? (Give an answer in Hz, to 3 significant figures.)

**2. Homework Equations**

f

_{(observed)}= f

_{(s)}x (V

_{w}/ V

_{w}+/- V

_{s})

f

_{(observed)}= f

_{(s)}x (V

_{w}+/- V

_{(obs)}) / V

_{w}

**3. The Attempt at a Solution**

a)

(2,410,000 Hz)(1540 m/s + .287 m/s) / 1540 m/s) = 2410449.136 Hz = 2.410449 MHz

b)

(2410449 Hz)(1540 / 1540 - .287) = 2410948.313 Hz = 2.410948 MHz

c) 2410948.313 - 2410000 = 948 Hz

a) is correct, I got that one right. b) and c) are wrong. I thought I did them correctly. Could someone please help?

Thank you!