Contextualization

Thermodynamics is the branch of Physics that studies the laws describing energy transfers, specifically heat. One of the most common situations where these concepts apply is in the study of gases and the 'work' a gas can perform. Work is understood as the energy transferred by applying a force over a displacement. In the case of gases, this force is applied by the expansion or contraction of the gas, and the displacement is the volume it occupies.

The 'work of a gas' is a fundamental concept in Physics and is applied in various areas of knowledge. The ability of a gas to perform work is the basis of operation for many technologies we use in our daily lives, such as internal combustion engines in cars, airplane turbines, or even your household refrigerator. However, it is worth noting that all these machines operate based on a series of gas transformations, which are processes where the variables that characterize the state of a gas, such as pressure, volume, and temperature, change in some way.

The work done by a gas in a transformation is, therefore, a form of energy that can be converted into another, and understanding this process is essential to comprehend how energy is used, and potentially wasted, in our world.

The purpose of this project is to give students a practical insight into the 'work of a gas' and its applications, through the creation of an educational project that can be developed in a group.

Practical Activity

Activity Title: Building a Vacuum Engine

Project Objective

Develop students' understanding of gas transformations and the work done by a gas, by building a simple homemade 'vacuum engine'.

Detailed Project Description

Students will build a vacuum engine using basic and easily accessible materials. This engine will demonstrate gas transformation and the work done by the gas when heat is applied, leading to gas expansion and, consequently, engine movement. The activity also emphasizes the importance of teamwork and communication among students.

Each group should document the entire process, from the planning phase to the final construction and testing of the engine. They should record their observations and conclusions during the experiment.

Required Materials

1. An empty soda can
2. Two cork stoppers
3. A plastic or metal straw
4. A candle
5. Matches or a lighter
6. Water
7. A stand for the can (can be a cup or any other sturdy object)
8. A large needle or small nail

Detailed Step-by-Step Guide for the Activity

1. One group member should pierce two holes in the soda can, one on each side, with the help of a large needle or a small nail. They should be aligned and close to the bottom of the can.
2. Insert a cork stopper into each hole made in the can.
3. Thread the straw through the two stoppers so that the straw is inside the can through the holes.
4. Fill the can halfway with water.
5. Heat the can with the candle.
6. When the water starts to boil, water vapors will be generated and will start to come out through the straw. This will demonstrate the work done by the gas (water vapor) in the expansion.
7. Allow the engine to cool. As it cools, the water vapor inside the can condenses, creating a vacuum that pulls the air (or water) back through the straw, causing the can to move in the opposite direction, demonstrating gas contraction.

Project Delivery

Groups should submit a report with the following topics:

1. Introduction: Describe what gas work is and its importance in the real world. Provide the project objective clearly and concisely.
2. Development: Describe in detail the engine construction process. Explain the theory behind gas work and how it applies to the engine. Present the steps you followed during the experiment and discussions throughout the experiment.
3. Results and Discussion: Discuss the results obtained during the experiment. Analyze your engine's performance and what these results indicate. You should include data visualizations, such as photos, graphs, and tables, if necessary.
4. Conclusions: Summarize the main points of the work, explaining the lessons learned and conclusions drawn from the project.
5. Bibliography: References for all materials consulted for the project development.

The report should be submitted within a week after the experiment. Each group member should contribute to the report writing, and this contribution should be clearly indicated in the document.