The heart of a man pumps 4 litres of blood through the arteries perminuteata pressure of 150 mm of m

Question

The heart of a man pumps 4 litres of blood through the arteries perminuteata pressure of 150 mm of mercury. If the density of mercury be $13.6 	imes 10^{3} \mathrm{~kg} / \mathrm{m}^{3}$ and $g=10 \mathrm{~m} / \mathrm{s}^{2}$ then the power (in watt) is

Professor PC Thomas Classes · Answer

(c) : Here, Volume of blood pumped by man's heart,\ $V=4$ litres $=4 	imes 10^{-3} \mathrm{~m}^{3} \quad\left(\because 1ight.$ litre $\left.=10^{-3} \mathrm{~m}^{3}ight)$\ Time in which this volume of blood pumps, $t=1 \mathrm{~min}=60 \mathrm{~s}$\ Pressure at which the blood pumps,\ $P=150 \mathrm{~mm}$ of $\mathrm{Hg}=0.15 \mathrm{~m}$ of Hg\ $=(0.15 \mathrm{~m})\left(13.6 	imes 10^{3} \mathrm{~kg} / \mathrm{m}^{3}ight)\left(10 \mathrm{~m} / \mathrm{s}^{2}ight)$\ $=20.4 	imes 10^{3} \mathrm{~N} / \mathrm{m}^{2}$\ $	herefore \quad$ Power of the heart $=\frac{P V}{t}$ $$ =\frac{\left(20.4 	imes 10^{3} \mathrm{~N} / \mathrm{m}^{2}ight)\left(4 	imes 10^{-3} \mathrm{~m}^{3}ight)}{60 \mathrm{~s}}=1.36 \mathrm{~W} $$