KDKA meteorologist Ray Petelin is back with another science lesson!By Ray Petelin

PITTSBURGH (KDKA) — Whether you say “slippy” or “slippery,” we are getting into the time of year where slipping and sliding occur.

Often, you think of ice or snow as the main cause of slipping.

Now, leaves are falling, and leaves left on the ground can make for a slick set up.

(Photo Credit: Ray Petelin)

First to understand why you slip, you need to know what stops you.

That is friction. Friction is the resistance that one surface or object encounters when moving over another. You can feel friction by rubbing your hands together.

The harder you push them together, and the faster you move them, the warmer your hands feel.

This heat is generated by the resistance, or friction. What does this have to do with slipping?

(Photo Credit: Ray Petelin)

Friction keeps us from slipping, and things that reduce friction make slipping more likely.

Those are lubricants. When thinking of lubrication, people think of oil or grease.

Lubricants can be dry, though. We call them “dry lubricants.”

While the name is not that creative, leaves would fall into this category.

Even though they are solids, they reduce the friction things have in contact with the ground, like tires and your shoes.

Leaves can make these surfaces more dangerous.

(Photo Credit: Ray Petelin)

A safe way to show this in action requires a smooth surface, rubber gloves and some leaves.

The rubber gloves will be a simulation for tires or the soles of your shoes.

When you put your hands on the smooth surface with these gloves on, it provides some resistance to reduce how much slipping occurs.

(Photo Credit: Ray Petelin)

Now, let’s add our dry lubricant, also known as leaves.

Now, do the experiment again. The friction isn’t there to hold you up anymore.

If you add water to the leaves, which also acts as a lubricant, they will become even more slick.

This means you need to be careful when there are leaves on the ground, especially slopes when you’re walking.

(Photo Credit: Ray Petelin)

You should also give extra stopping distance when driving a car, since the leaves can prevent you from slowing down, just like snow.

(Photo Credit: Ray Petelin)

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