An ultrasound wave with a frequency of 4 MHz is reflected from blood cells in a blood vessel. A frequency decrease, Af, of -0.5 Hz is detected. The speed of ultrasound waves in blood is 1570 m/s. (a) Are the blood cells moving toward or away from the transducer? (b) Determine the relative speed of the blood within the blood vessels in the direction of the sensor? (c) If the transducer was transmitting ultrasound waves at an angle of theta with respect to the blood flow explain how this would affect the observed frequency shifts.

An ultrasound wave with a frequency of 4 MHz is reflected from blood cells in a blood vessel. A frequency decrease, Af, of -0.5 Hz is detected. The speed of ultrasound waves in blood is 1570 m/s. (a) Are the blood cells moving toward or away from the transducer? (b) Determine the relative speed of the blood within the blood vessels in the direction of the sensor? (c) If the transducer was transmitting ultrasound waves at an angle of theta with respect to the blood flow explain how this would affect the observed frequency shifts.