Answer
The average mechanical power output of the heart is 5.25 Watts.
Work Step by Step
We can find the volume of blood pumped into the aorta each second:
$5.0~L/min \times \frac{1~m^3}{10^3~L} \times \frac{1~min}{60~s} = 8.33\times 10^{-5}~m^3/s$
We can find the area of the aorta:
$A = \pi~r^2 = (\pi)(0.009~m)^2 = 2.54\times 10^{-4}~m^2$
We can find the speed $v$ of the blood in the aorta:
$A~v = 8.33\times 10^{-5}~m^3/s$
$v = \frac{8.33\times 10^{-5}~m^3/s}{A}$
$v = \frac{8.33\times 10^{-5}~m^3/s}{2.54\times 10^{-4}~m^2}$
$v = 0.328~m/s$
We can find the heart's power output:
$P = F~v = (16~N)(0.328~m/s) = 5.25~Watts$
The average mechanical power output of the heart is 5.25 Watts.
