In humans, blood flows from the heart into the aorta, from which itpasses into the major arteries. These branch into the smallarteries (arterioles), which in turn branch into myriads of tinycapillaries, see the figure. The blood returns to the heart via theveins. The radius of the aorta is 1.0 cm and the blood passingthrough it has a speed of about 32 cm/s. Atypical capillary has a radius of about 4 × 10-4cm, and blood flows through it at a speed of about 5 ×10-4 m/s. Calculate the average speed of blood flow inthe major arteries of the body which have a total cross-sectionalarea of about 2.1 cm2.
Explanation / Answer
The capillary info is irrelevant because they dont tell youhow many capillaries there are. . BUT... the idea is that the total flow rate in the aorta(there's only one of those) is equal to the flow rate through themajor arteries, so... . flow rate in aorta = flow rate in arteries . speed * area = speed * area . 32cm/s * * 1.02 = speedin arteries * 2.1 . speed in arteries = 47.87cm/s which is also 0.4787m/s