Question

The left ventricle of a resting adult’s heart pumps blood at a flow rate of 83.0cm3/s, increasing its pressure by 110 mm Hg, its speed from zero to 30.0 cm/s, and its height by 5.00 cm. (All numbers are averaged over the entire heartbeat.) Calculate the total power output of the left ventricle. Note that most of the power is used to increase blood pressure.

(a) 3.88 W
(b) 1.33 W
(c) 0.42 W
(d) 4.27 W

Answer 1

To calculate the total power output of the left ventricle, we need to consider the changes in pressure, speed, and height of the blood. We calculate the work done to increase the blood pressure, the work done to increase the speed of the blood, and the work done to increase the height of the blood. Finally, we divide the total work done by the time taken to pump the blood to find the total power output.

Step-by-step explanation:

To calculate the total power output of the left ventricle, we need to consider the changes in pressure, speed, and height of the blood. Power is given by the equation power = work / time. First, we calculate the work done by the left ventricle to increase the blood pressure. The work done is equal to the change in pressure times the change in volume, which is given by the formula work = pressure x volume.

Next, we calculate the work done to increase the speed of the blood. The work done to change the speed of an object is given by the formula work = 1/2 x mass x (final velocity^2 - initial velocity^2). In this case, the mass of the blood is given by its density multiplied by its volume.

Finally, we calculate the work done to increase the height of the blood. The work done to change the height of an object is given by the formula work = mass x acceleration due to gravity x height.

Once we have calculated the total work done, we divide it by the time taken to pump the blood, which is given by the flow rate, to find the total power output of the left ventricle.