Purpose
To demonstrate that by doing work on a system, we can increase the temperature of that system, leading to ignition.
Materials
- Fire piston apparatus
- Very small piece of cotton (2-3 threads)
- Pencil (for placement)
Procedure
- Setup Introduction:
- Show the fire piston to the class, ensuring they understand the setup without revealing its name yet.
- Cotton Placement:
- Take a very small wisp of cotton and use a pencil to poke it to the bottom of the tube.
- Demonstration:
- Dim the lights to enhance visibility.
- Have students observe what happens when work is done on the system: apply constant pressure and quickly ram the plunger down.
- Ignition Observation:
- The cotton will ignite due to the rapid compression of gas and the resulting increase in temperature.
- Repetition:
- Repeating the demonstration is possible; however, a delay must be introduced due to moisture produced in the process.
- Principle Explanation:
- Explain that this phenomenon is similar to the principle behind a diesel engine.
Conclusion
This experiment effectively illustrates how work done on a gas can lead to a significant increase in temperature, resulting in ignition.