Professor Walter Lewins was born on January 29, 1936. He is a Dutch astrophysicist and former professor of physics at the Massachusetts Institute of Technology (MIT).
In the video below, Professor Lewins draws dotted lines so fast and effortlessly! You can hear the chalk hitting the board at every dot but it seems like his hand isn’t moving up and down.
Can be explained by Physics
It’s really more interesting and impressive than it sounds.
But being a physics professor, he said that drawing these dotted lines can be explained by, well, physics.
You have to hold it [the chalk] very tight at the end. And then you move it downwards but you let it jump. It does that by itself because your force down becomes larger than the frictional force. And then the chalk breaks loose. But since you keep pushing on it, it goes back to the board,
He said as he taught a student the trick.
Sound easy enough, right?
Source: ItMustBeCollege on YouTube