Why we put sand on icy sidewalks and roads?

Explanation

### Step-by-Step Solution

1. **Understanding the Problem**: The question asks why sand is put on icy sidewalks and roads. We need to analyze the effects of sand on these surfaces.

2. **Identifying the Conditions**: Icy sidewalks and roads are slippery due to the presence of ice, which has a low coefficient of friction. This makes it difficult for people to walk safely.

3. **Role of Friction**: Friction is a force that opposes motion. It is crucial for walking and driving because it allows us to grip the ground. The more friction there is, the easier it is to walk or drive without slipping.

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