So, the upshot seems to be that if you use magnets on iron-coated sand, you can make it flow uphill? I mean, I guess the flow patterns are kinda interesting, with the sand grains on top being less ...

If asked to provide an example of friction at work, many people begin to rub their hands together and speak of the heat being generated. This is the traditional example of friction; however, within a ...

Q: Tim, I read a column on your website about rock retaining walls. I’m having a hard time believing you can build a lasting wall and not use mortar between the stones. I’d love to just build a wall ...