Jennifer R. Vail

I think friction has always kept us on our toes.

Most cases in science, a law is a law and it doesn't get broken.

But with our laws of friction, you find certain materials might behave different ways because of how their bonds are.

Or at certain speeds, well, those laws just don't come into play because friction also has a component where it creates heat.

And heat then changes materials and it changes your whole system.

So there's always surprises.

When I worked in my lab, I would think I was getting a handle on what my materials were doing.

I could change something like, you know, the environment it was in, put it into vacuum or change the temperature or even the load or the speed.

And all of a sudden the friction would start doing something a little bit different.

There's still ways friction keeps us on our toes.

It's not always straightforward.

And that's why our journey with understanding friction has been so interesting.

It's really amazing if you think about any of your writing utensils that they work the way they do.

And you've definitely noticed when the friction is not optimized, because, you know, either the crayon will chatter, I'll call it, it sort of

sticks and jumps around the page, it's not a smooth line.

Or with your pencil, if the graphite isn't great, it gets that scratchy and that awful sound that gives you goosebumps.

And it's because it has too high friction, and it's scratching and jumping across the paper.

So with crayons, it's this wonderful combination of the material that you want to transfer to your paper with having some wax, which is a solid lubricant,

We're used to lubrication being water or oils, but there are solids and waxes are some of them.

And by having that perfect balance of friction, you're able to write on the paper smoothly, but still transfer the material of the crayon to the paper.