Preview - Thermal Equilibration - Comparing Individual And Aggregate Levels Of A System

Using a Model to Explore Thermal Equilibration

Start by opening the Thermal Equilibration model in Netlogo:

  1. Download the Thermal Equilibration Netlogo model. 
  2. Open NetLogo (download link), go to File>Open…, and select the Thermal Equilibration Netlogo model.

WHAT IS THE MODEL?
This model simulates the thermal equilibration of two fluids according to principles of Newtonian mechanics. Each dot represents a particle and its color corresponds to its kinetic energy, with darker reds representing greater kinetic energy. The white strips represent regions of the container over which the average kinetic energy can be measured, with the left side starting with greater kinetic energy (temperature) than the right side.

HOW IT WORKS
Individual particles are randomly distributed throughout a closed box. They are given random directions and a set amount of energy. When the simulation starts, the particles begin to move in straight lines in random directions with a speed proportional to their energy. When they collide with the edge of the box, they reflect without losing energy. When they collide with another particle, they exchange energy with that particle according to the laws of conservation of momentum and energy.

HOW TO USE IT

  1. Run simulation and observe the aggregate behavior of the system.
    1. Press the “setup” button to set the initial conditions of the world at the slider values you have chosen. 
    2. Press the “go” button to start the simulation.
    3. Observe what happens to the plots and monitors that read-out average values for the system.
      1. The “total KE of the system” graph records the total energy for the whole system over time.
      2. The “avg-KE” graph records the average kinetic energy over time for the left and right sides of the system, as well as the predicted value for the average kinetic energy of the left side of the system. 
      3. The “time-to-equilibrium” monitor records the first time at which the average kinetic energies of the two sides of the box are approximately equal.
    4. Answer question 3 below based on your observations.
       
  2. Run simulation and observe the aggregate behavior of the system.
    1. Press the “setup” button to set the initial conditions of the world at the slider values you have chosen. Set the simulation speed to “normal speed”. 
    2. Right click on a particle in the system and choose “h-particle X” and then “watch h-particle X”. This spotlights a single particle.
    3. Press the “go” button to start the simulation.
    4. Observe behavior of an individual particle. Notice what leads to changes in behavior and how its color relates to its speed (kinetic energy). 
    5. Answer question 4 below based on your observations.
       

Questions

Please answer the questions below.

Which level of a thermal equilibration system is being described? 

"Cold milk is poured into a cup of hot tea."

Which level of a thermal equilibration system is being described?

“A particle is moving around within a fluid.”

Using the Netlogo model, what behavior do you observe on the aggregate level? How does this compare to your prediction in Step 1?

Using the Netlogo model, what behavior do you observe on the individual level? How does this compare to your prediction in Step 1?

Notes

These notes will appear on every page in this lesson so feel free to put anything here you'd like to keep track of.