1. The problem statement, all variables and given/known data A Doppler blood flow unit emits ultrasound at 5.0 MHz. What is the frequency shift of the ultrasound reflected from blood moving in an artery at a speed of 0.20 m/s? Express your answer using two significant figures. 2. Relevant equations f' = f0(v/v-Vs) frequency shift = f' - f0 f0 = 5*10^6 Hz v = 1500 m/s (assumed) Vs = 0.20 m/s 3. The attempt at a solution Plugging in the numbers we get the following equation for frequency shift: (5*10^6)*[1500/(1500-0.2)]-5*10^6 Which comes out to approx 666 Hz. or 6.7 *10^2 Hz using 2 significant figures. However, this problem comes from an online hw set and according to that 6.7 *10^2 is not the correct solution. Does anyone have an idea of what I am doing wrong? Thanks in advance for any and all help!