Answer to Question #249830 in Molecular Physics | Thermodynamics for shami

Question

The heart consumes 350 kJ of energy per day. What is heart efficiency if it strikes 62 beats per minute and makes a work of 1.1 J per one stroke?

Answer 1

The efficiency is given as follows:

$$\eta = \dfrac{W_{done}}{Q_{cons}}\times 100\%$$

where $W_{done}$ is the useful work done by the heart, $Q_{cons} = 350kJ$ is the consumed energy. The useful work can be found as follows:

$$W_{done} = 1.1J\times 62\times 1440 = 98208J = 98.208kJ$$

where $1440$ is the number of minutes in one day.

Thus, obtain:

$$\eta = \dfrac{98.208kJ}{350kJ}\times 100\% \approx 28\%$$

Answer. 28%.