I found that when I read about these forces, text-based explanations never really solidified the concepts for me. To really get a sense of how the forces worked, I had to build lots of force graphs and tweak the parameters manually to see what each of them did.
So I got really excited when I discovered this testing ground for force directed graphs, built especially for version 4 of D3:
Made by Steve Haroz, it’s a brilliantly simple way to allow you to experiment quickly and easily with all the different settings available for force graphs. Use it to develop an intuitive sense of what each force does and how each of the force parameters affects the final result.
Hope you found that useful! Click here to view to the rest of the force directed graph series