The human heart discharges 75ml of blood at each against a pressure of 0.1 m of Hg. Calculate the power of the heart assuming that the pulse frequency is 80 beats per minute. Given, density of mercury =13.6×103 kg/m3.
Here,
Volume of blood discharged per beat, V = 75 ml = 75 × 10⁻⁶ m³
Pressure, P = 0.1 m of Hg
P = 0.1 × (13.6 × 10³) × 9.8 N/m² [from P = hρg]
Work done per beat = PV
Total work done in 80 beats = PV × 80
As Power = Work / Time
∴ Power = (PV × 80) / t
= (0.1 × 13.6 × 10³ × 9.8 × 75 × 10⁻⁶ × 8) / 60
Power = 1.33 watt