A human heart pumps 60 cc of blood through the arteries at each beat against an average pressure 10 cm of mercury.   If the pulse beats 72 times in a minute, the pumping power of heart will be nearly(Density of mercury  =   13.6 gm/cc,     $g=10cm/s^2$)

$Power=\frac{Work}{time}=\frac{Pressure\cdot Volume}{t}=\frac{hdg\cdot V}{t}$

$given height h=10cm=0.1m;$

$density of mercury d=13.6x{10}^{3}kg/m^3;$

$acceleration due to gravity g=10m/s^2;$

$volume v=60x{10}^{-6}{m}^3$

$time for 1 heart beat=\frac{60}{72}$

$Power\text{=}\frac{0.1\times 13.6\times {10}^3\times 10\times 60\times {10}^{-6}}{\frac{60}{72}}$

$Power\text{=}0.9792\simeq 1Watt$