A Doppler blood flow unit emits ultrasound at 4.2 MHz. What is the frequency shift of the ultrasound reflected from blood moving in an artery at a speed of 0.25 m/s? A. Understand the problem - list the relevant quantities. For each quantity list a name, symbol, units, and either the given number or mark as unknown. B. Identify assumptions - write what you are assuming/idealizing about how the blood is moving in the vein and the ultrasonic signal. C. Represent the situation physically - draw and label a diagram of the situation. An appropriate diagram should always be a professional representation that includes specific details helpful to the situation (not just a simple picture!). D. Represent principles symbolically - Write the name of any equations you'll use and write the equation. If there are conditions for this equation being used, explain how these are met. E. Find unknown(s) symbolically - without numbers, find any unknown(s) in terms of symbols representing known quantities. F. Plug in numbers - plug numbers (with units) into your symbolic answer! G. Are the units correct? State the units you expect the unknown quantity to have. Show that the algebraic expression of your final answer reduces (cancels out) to have those same units. H. Is your numerical answer reasonable for the problem? Did you expect your final answer to be a scalar or a vector? Is that what you got? What sign and/or direction did you expect your final answer to have? Is that what you got? Is the size of the numeric answer reasonable? Compare this number to a value you know (or Google). Does the physics of your symbolic answer match the real world physics? Analyze your symbolic solution. Use your real-world intuition to decide if the blood in the vein was moving much slower/faster, would you expect the time to increase, decrease, or stay the same? Does your symbolic solution match this conclusion? (you may need to do some math to help you conclude this) Be sure to explain your reasoning. I.