This week my first year students have started Thermal physics and doing the Particle nature of matter activity . This includes something about the interatomic force (off syllabus but worth knowing). Several students have been asking me what this graph represents so I thought I'd make a simulation to help. I started by trying to fake it in Algodoo by using springs, that worked ok but I couldn't plot the graph so turned to GeoGebra. I started with the equation which is of the form Ax^-n - Bx^-m . Then I plotted a line that had the correct shape. Finally I added the force vector with a length that was determined by the same equation.

Now you can move the right hand atom and see how the changing force is represented on the graph

Happy now?