Solution of question The work done by the heart if it's beats 72times per minute

To find the work done by the heart if it beats 72 times per minute, we need to know the amount of work done in one beat.

The work done by the heart can be calculated by multiplying the force exerted by the heart with the distance over which the force is exerted. However, it is difficult to quantify the force and distance in this case.

An alternative approach is to estimate the work done by the heart based on the average cardiac output. The cardiac output is the volume of blood ejected by the heart per minute. It is typically measured in liters per minute (L/min).

The average cardiac output for a resting adult is around 5 liters per minute (L/min). Therefore, the work done by the heart can be estimated as the product of the cardiac output and the pressure against which the heart pumps blood.

Assuming a pressure of 100 mmHg (millimeters of mercury), we can calculate the work done using the following formula:

Work = Cardiac Output * Pressure

Substituting the values, we get:

Work = 5 L/min * 100 mmHg

To convert the units, we need to convert liters to cubic meters and millimeters of mercury to pascals.

1 L = 0.001 m^3 (cubic meter)
1 mmHg = 133.32 Pa (pascal)

Converting the units, we have:

Work = 5 * 0.001 m^3/min * 133.32 Pa

Simplifying, we get:

Work = 0.6666 m^3*Pa/min

So, the work done by the heart in one minute is approximately 0.6666 m^3*Pa/min.

Now, to find the work done per beat if the heart beats 72 times per minute, we divide the total work done in one minute by the number of beats per minute:

Work per beat = Total Work / Number of Beats

Work per beat = 0.6666 m^3*Pa/min / 72 beats/min

Calculating the result, we get:

Work per beat ≈ 0.00925 m^3*Pa/beat

Therefore, the work done by the heart if it beats 72 times per minute is approximately 0.00925 m^3*Pa/beat.