The heart of a man pumps 5 liters of blood through the arteries per minute at a pressure of 150 mm of mercury. If the density of mercury be `13.6xx10^(3) kg//m^(3)` and `g=10 m//s^(2)` then the power of heat in watt is :

Options

A. `3.0 W`
B. `1.50W`
C. `1.70 W`
D. `2.35 W`

Answer

`(3)`

Explanation

Here, Volume of blood pumped by man.s heart. `V = 5 litres = 5 xx 10^(-3)m^(3)` (because `1 litre = 10^(-3) m^(3))`
Time in which this volume of blood pumps, `t = 1 min = 60 s`
Pressure at which the blood pumps, ` P = 150 mm of Hg = 0.15 m of Hg`
` = (0.15m)(13.6 xx 10^(3) kg / m^(3))(10 m/s^(2))`
`(because P = h rho g)`
`= 20.4 xx 10^(3) N/m^(2)`
therefore Power of the heart =` (PV)/t `
` = (20.4 xx 10^(3) N/ m^(2))(5 xx 10^(-3) m^(3))/(60s) = 1.70 W`