The human heart has to pump the average adult\'s 5.8 L of blood through the body
ID: 1477078 • Letter: T
Question
The human heart has to pump the average adult's 5.8 L of blood through the body every minute. The heart must do work to overcome frictional forces that resist the blood flow. The average blood pressure is 1.4×104 N/m2 .
Part A
Compute the work done moving the 5.8 L of blood completely through the body, assuming the blood pressure always takes its average value. Hint: When the heart contracts, it applies force to the blood. Pressure is just force/area so we can write work = (pressure)(area)(distance). But (area) (distance) is just the blood volume passing through the heart.
Part B
What power output must the heart have to do this task once a minute?
Explanation / Answer
A)
work = pressure x area x distance
work = pressure x volume
work = 1.4 x 10^4 N/m² x 5.8 x 10^-3 m³ = 81.2 J
B)
power = work/time
power = 81.2 J / 60 s = 1.3533 W
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