Two-Dimensional Diatomic Model

Description

This simulation shows a two-dimensional model of a diatomic molecule using hard disks connected by a spring.  Each disk interacts with the walls  via a strong short-range repulsive force.  The mass ratio of the two disks is 1:4.  You may drag either mass at any time but this will change the internal energy.

The brown bar on the right displays the total kinetic energy of both masses.  The blue bar displays the energy stored in the spring.

Questions

Be sure to consider the two-dimensional nature of the above simulation.

• Is the internal energy constant?

• Estimate the internal energy of the system?

• What is the average kinetic energy of each mass?

• What is the ratio of the average total kinetic energy to the average potential energy?

Answers

• It depends on how you define the system.  If the system is defined to be the masses and the spring, the internal energy is almost constant.  Some energy is stored during a collision with a wall.  If the system includes the wall, then the internal energy is constant.

• The internal energy of system is approximately 80.8 J.

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Features of this Script

This script demonstrates the use of the following methods:

• Animator.addInteraction(int id1, int id2, String force)
• Animator.addConnectionSpring(int id1, int id2)
• Animator.setDragable(int id, boolean dragable)
• Animator.setForce(int id, String fx, String fy, double x0, double y0, double vx0, double vy0)
• Animator.swapZOrder(int id1, int id2)

The Multiplexer filter is used to collect x and y data from the two masses in order calculate the potential energy.

Required Resources

Jar files:  Animator4_.jar, Bar4_.jar, DataTable4_.jar, Filters4_.jar, STools4.jar
Images:  none

Credits

Script by Wolfgang Christian
Questions by Wolfgang Christian.
Java applets by Wolfgang Christian.