Hi, I'm Ira Flato, and this is Science Friday. We're sliding into your feed to tackle a slippery

wintertime question about ice. Now, ice is classified by scientists as a mineral, as long as it's

naturally recurring. So ice in a snowbank or a glacier, it's a mineral, it's a rock.

So you may have wondered as you strapped on your ice gates or struggled down a frozen sidewalk,

if ice is a rock, just why is ice slippery?

There's been a common answer to that question.

That feels a little bit slippery now.

Why?

Well, here to help with this is Dr. Robert Carpick.

He studies tribology. That's the science of things like friction, wear, lubrication, and is the

John Henry Town Professor in the Department of Mechanical Engineering and Applied Mechanics

at the University of Pennsylvania in Philadelphia.

Welcome back to Science Friday. Thank you so much, Ira. Great to be here.

Nice to have you back. First, I've got to ask you, what is the definition of tribology? Where does that

originate from? It's a great question, you know, for quite some amount of time, researchers in the area just called themselves

friction engineers and friction and liberation engineers and adhesion scientists. And it was all a bit

too many words. And a scientist named Peter Jost in the United Kingdom decided in 1960s, we need

a name for this field, and he proposed

tribology. It comes from the Greek word tribos, which means rubbing or sliding. And he did

what any good Englishman would do. He asked the Oxford English Dictionary to give it their blessing,

and they did. And the word was born then, and that's how the field's been known, although it's still

not so widely known a term. So I appreciate you giving me a chance to promote it a bit.

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