The heart of a man pumps 5 litres of blood through the arteries per minute at a pressure of 150mm of mercury. If the intensity of mercury be 13.6 x 10³ kg/m³ and g=10 m/s² then the power of heart in watt is
Options
(a) 3
(b) 1.5
(c) 1.7
(d) 2.35
Correct Answer:
1.7
Explanation:
WORK DONE W = F X D
F = PA (PRESSURE X AREA)
OR W = P A.D = P (AD) = P V
OR WORK DONE = PRESSURE X VOLUME
Given P = 150mm OF Hg = 105 * 150/760
= 15 x 105 / 76 Pa
Volume, V = 5L = 5000 cm3 = 5×10-3 m3
So, W = PV = (15 x 105 / 76 ) x 5×10-3
Work Done = 98.68 Joules
Now pumping of 5L of blood is done in 1 min = 60 seconds
So, Power = Work done / time
OR POWER = 98.68 /60 = 1.64 watts