Walter Lewin Dotted Lines

As everyone in the world of physics knows, Walter Lewin has the ability to draw dotted lines with perfection. They are perfectly straight and spaced out, and he can draw them in mere seconds. To do this, as a master of physics he can figure out how to do it with ease and teach his students some extra physics as well. To draw his lines, he must have calculated the kinetic friction of the chalk on the chalkboard, and then held the chalk at a certain angle so that the sin and cos forces will be perfect so that when he moves the chalk quickly it will skip like it does and make the dotted lines. It is essential that he goes fast so that the line stays straight and this is how he draws those famous lines.