Teaching Physics with the Physics Suite

Edward F. Redish

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The main blood vessel carrying blood out of your heart is the aorta. It carries blood down towards the legs. In your abdomen it splits into two, the common iliac arteries, as shown in the figure at the right. The diameter of a typical aorta is 2 cm, while the common iliac arteries typically have diameters of about 1 cm.

(a) The speed of the blood in the aorta can be measured. A typical value is v_A = 30 cm/s when the heart is contracting. Find the rate of blood flow in the aorta (current, Q_A, in cm³/s) and the speed of the blood flowing in the iliac arteries (v_I). Explain your reasoning.

(b) As the blood flows around through the system of arteries and veins, the blood pressure drops slowly. While the blood is flowing smoothly, would you expect to see a larger pressure drop from the beginning to end of 10 cm of aorta or from the beginning to the end of 10 cm of iliac artery? Explain your reasoning.