The image depicts a beaker containing a liquid being heated by a flame beneath it. This setup is commonly used to illustrate the
First Law of Thermodynamics, which is also known as the
Law of Conservation of Energy. Let's break down the problem and explain the solution step by step.
---
Understanding the First Law of Thermodynamics
The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another. Mathematically, it is expressed as:
\[
\Delta U = Q - W
\]
Where:
- \(\Delta U\) is the change in internal energy of the system.
- \(Q\) is the heat added to the system.
- \(W\) is the work done by the system.
In this context:
- The
system is the liquid in the beaker.
- The
surroundings are everything outside the beaker, including the flame and the environment.
---
Analyzing the Image
1.
Heat Addition (\(Q\)):
- The flame beneath the beaker represents an external source of energy (heat) being added to the liquid.
- As the flame heats the liquid, thermal energy is transferred from the flame to the liquid, increasing the temperature of the liquid.
2.
Change in Internal Energy (\(\Delta U\)):
- The increase in temperature of the liquid indicates an increase in its internal energy (\(\Delta U > 0\)).
- The bubbles forming in the liquid suggest that some of the liquid may be vaporizing, which requires additional energy (latent heat of vaporization).
3.
Work Done (\(W\)):
- In this scenario, the liquid is not expanding against any external pressure (e.g., no piston movement). Therefore, the work done by the system (\(W\)) is negligible or zero.
---
Applying the First Law
Using the equation \(\Delta U = Q - W\):
- Since \(W \approx 0\) (no significant work is done by the system),
- The change in internal energy (\(\Delta U\)) is directly proportional to the heat added (\(Q\)).
Thus:
\[
\Delta U = Q
\]
This means that the energy added to the system (in the form of heat from the flame) is entirely converted into an increase in the internal energy of the liquid. No energy is "lost"; it is simply transformed from one form (thermal energy of the flame) to another (internal energy of the liquid).
---
Conclusion
The image illustrates the principle of energy conservation. The heat supplied by the flame is absorbed by the liquid, increasing its internal energy. This process adheres to the First Law of Thermodynamics, which ensures that energy is conserved and cannot be created or destroyed.
Final Answer
\[
\boxed{\text{The First Law of Thermodynamics is demonstrated as the heat from the flame increases the internal energy of the liquid, with no energy lost.}}
\]
Parent Tip: Review the logic above to help your child master the concept of first law of thermodynamics worksheet.
