Case1: If you place an empty chair on the ground and drag it to a little distance across the floor.
Case 2: Now, ask you friend to sit on the chair and try to drag the chair across the floor. Answer the following questions
What do you understand about frictional force from this activity?

Explanation

### Step-by-Step Solution:

1. **Understanding the Setup**:
- In Case 1, we have an empty chair placed on the ground. When we drag it across the floor, we are applying a force to overcome the friction between the chair and the floor.
- In Case 2, a friend sits on the chair, increasing its total mass. When we try to drag the chair again, we are applying force to overcome the increased friction.

2. **Analyzing the Forces**:
- In Case 1, the frictional force is determined by the weight of the empty chair. Let's denote the mass of the empty chair as \( M_1 \).
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