Here, Volume of blood pumped by man's heart, V=5 litres =5×10−3m3(∵1. litre =10−3m3) Time in which this volume of blood pumps, t=1min=60s Pressure at which the blood pumps, P=150mm of Hg=0.15m of Hg =(0.15m)(13.6×103kg∕m3)(10m∕s2)(∵P=hρg) =20.4×103N∕m2 ∴ Power of the heart =