Contextualization

The theme of 'Heat Exchange' is one of the most fascinating in physics, as it allows us to understand various situations in our daily lives. Have you ever wondered why you feel cold when you get out of the shower? Or why an ice cream melts if it's left out of the freezer? These are situations that can be explained through the understanding of heat exchange. Therefore, this part of the physics curriculum is extremely relevant and interesting, as it allows us to understand common phenomena in our daily lives.

Thermodynamics, the part of physics that deals with studying heat exchange, has many practical applications. For example, in engineering, it is essential for the design of combustion engines, refrigerators, air conditioning systems, and many other devices that surround us.

Theoretically, heat exchange is based on some fundamental concepts of physics. The first of these is the concept of energy, particularly thermal energy. Furthermore, it is essential to understand the mechanisms of heat transfer - conduction, convection, and radiation - and how they occur in different materials. Finally, it is necessary to understand how heat can change the temperature of materials and cause changes in state.

Practical Activity

Activity Title: 'Construction and Analysis of an Eco-Friendly Refrigerator'

Project Objective

This project aims to provide students with a practical understanding of the concepts of heat transfer, thermal energy, thermal insulation, and changes in state, through the construction of a simple eco-friendly refrigerator. In addition to physics, the activity involves concepts of engineering, ecology, and resource management.

Detailed Project Description

Students, in groups of 3 to 5, must design, build, and test an eco-friendly refrigerator that uses water evaporation to cool its interior, a process known as evaporative cooling. During the process, they must monitor and record the temperature and state changes inside the refrigerator. After construction, students must conduct tests to verify the effectiveness of their refrigerator, measuring the internal and external temperatures at regular intervals and analyzing the results.

Required Materials

1. Two containers of different sizes that can fit into each other (for example, two buckets, where one fits inside the other).
2. Sand.
3. Water.
4. Cloth or towel.
5. Thermometer.
6. Stopwatch.
7. Food or drinks to be cooled for testing.

Detailed Step-by-Step Guide for the Activity

1. Fill the larger bucket with a layer of sand about 5 centimeters thick.
2. Place the smaller bucket inside the larger one. The edges of the two containers should be at the same height.
3. Fill the space between the two buckets with sand.
4. Moisten the sand with water, but do not soak it. The sand should be damp.
5. Place the food or drinks to be cooled in the smaller bucket.
6. Cover the opening of the buckets with a damp cloth or towel.
7. Record the initial temperature inside the bucket and also the ambient temperature.
8. Leave the system for a few hours in a place where it can receive wind (but not directly in the sun).
9. Every hour, record the temperature inside the bucket and the ambient temperature.
10. Continue the experiment for at least 12 hours.

Students should note all their observations, including how temperatures changed over time and any changes in the sand's humidity or the cloth used to cover the buckets.

Project Deliverables

After completing the practical part of the project, students must write a detailed report with the following topics: Introduction, Development, Conclusions, and Bibliography used.

• Introduction: In this topic, students must contextualize the theme, explain its relevance and real-world application, and explain the project's objective.
• Development: Here, students must detail the theory behind heat exchange and the evaporative cooling process, explain in detail how the refrigerator was built, indicate the methodology used to collect and analyze the data, and present and discuss the results obtained.
• Conclusion: Students must summarize the main points of the work, explain the learnings obtained, and draw conclusions about the effectiveness of the eco-friendly refrigerator they built.
• Bibliography: Finally, students must indicate the sources they used to support the work, such as books, web pages, and videos.

The reports must be submitted in digital format, with the results organized clearly and logically, and the conclusions well-founded.