What frequency does the blood receive? What frequency return

CMATT

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 OpenStaxCollege 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 (Vw / Vw +/- Vs)

f(observed) = f(s) x (Vw +/- V(obs)) / Vw

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!

Related Introductory Physics Homework Help News on Phys.org

CMATT

NEVERMIND! I solved it

"What frequency does the blood receive? What frequency return"

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving