Question

The human heart is a powerful and extremely reliable pump. Each day it takes in and discharges about 7300 L of blood. Assume that the work done by the heart is equal to the work required to lift that amount of blood a height equal to that of the average citizen of Atlantic Falls, approximately 1.6 m. The density of blood is 1050 kg/m3. What is the heart's power output in watts?

Answer 1

1.39 W

Step-by-step explanation:

The volume of blood is

`V=7300 L = 7.3 m^3`

the density is

`\rho = 1050 kg/m^3`

So the total mass of blood lifted in one day is

`m=\rho V=(1050 kg/m^3)(7.3 m^3)=7665 kg`

So the total work done is:

`W=mgh=(7665 kg)(9.8 m/s^2)(1.6 m)=1.2\cdot 10^5 J`

The total time taken is one day, so

`t=24 h = 86400 s`

So the power output is

`P=(W)/(t)=(1.2\cdot 10^5 J)/(86400 s)=1.39 W`