Workout: Atomic and molecular forces


Read the webpages Interatomic forces and The Lennard-Jones Potential 


To give you some practice on working with potential energy graphs, go to the PhET simulation Energy Skate Park to perform a few tasks.

Answer these questions

1. On the Intro tab, use the default track (looks like a "U"). Briefly describe the horizontal component of the force the skater experiences when they are on the left side, right side, and middle of the path. 


Now, go to the Playground tab and t make a track that looks like the Lennard-Jones Potential described in the reading as shown below. Set the friction tab to 0. (There's no friction between individual atoms!)

2. Start the skater high on the left and watch them go on the track. Describe what happens focusing on their speed and when they slow down, speed up, or change direction.

3. What is the direction of the horizontal component of the force on the skater when they are on the right, on the left, and near the bottom of the track?

4. Explain how you decided in which direction the force acted on the skater in each case.


Dave Buehrle, Fall 2016
Joe Redish 2/26/19

Article 552
Last Modified: February 27, 2019