When surfaces in contact are…..friction between them….instead of….. .

Explanation

To solve the fill-in-the-blank question regarding friction between surfaces in contact, we can follow these steps:

### Step 1: Identify the Context
We need to understand the relationship between the smoothness of surfaces in contact and the frictional force that arises between them.

### Step 2: Analyze the Smoothness of Surfaces
When surfaces are described as "smooth," it generally implies that they have a low coefficient of friction. However, the question suggests a counterintuitive scenario where increased smoothness leads to increased friction.

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