Chapter 18, Problem 1E

What is the first law of thermodynamics, and how does it relate to energy use?

Interpretation Introduction

To determine:

First law of thermodynamics and how does it relate to energy use.

Answer to Problem 1E

Solution: First law of thermodynamics:

It is the difference between the heat supplied, $\text{Q}$ to the system and the work done, $\text{w}$ by the system on its surrounding is equal to the change in internal energy of a closed system.

Mathematically,

  $△\text{U}=Q-W$

It is related to energy use by the statement that it is based on conservation of energy which means energy can neither be destroyed nor be created but it can be transformed from one form to other.

Explanation of Solution

The first law of thermodynamics states that the difference between the heat supplied to the system, $\text{Q}$ and the work done, $w$ by the system on its surrounding is equal to the change in internal energy of a closed system.

  $△\text{U}=Q-W$

This is based on conservation of energy principle because here all the heat energy is converted to other forms of energy.

Conclusion

First law of thermodynamics is based on conservation of energy.