Answer
The average speed of the blood flow in the major arteries is 90 cm/s
Work Step by Step
We can assume that the volume flow rate of the blood is constant throughout the body. The speed of the blood flow in the aorta is 40 cm/s and the radius of the aorta is 1.2 cm. The volume flow rate is the speed of the liquid times the cross-sectional area of the blood vessel. Let $v_2$ be the average speed of the blood flow in the major arteries.
We can find the speed $v_2$.
$v_2~A_2 = v_1~A_1$
$v_2~A_2 = v_1~\pi~r_1^2$
$v_2 = \frac{v_1~\pi~r_1^2}{A_2}$
$v_2 = \frac{(0.40~m/s)(\pi)(0.012~m)^2}{2.0\times 10^{-4}~m^2}$
$v_2 = 0.90~m/s = 90~cm/s$
The average speed of the blood flow in the major arteries is 90 cm/s.
