Which type of friction comes into play when a book kept on cylindrical pencils is moved by pushing ?

Options

A. Rolling friction
B. Static friction
C. Sliding friction
D. None of the above

Answer

To solve the question, "Which type of friction comes into play when a book kept on cylindrical pencils is moved by pushing?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Situation**: We have a book placed on top of cylindrical pencils. When we push the book, it starts to move.

2. **Understand the Forces Involved**: When the book is pushed, it experiences frictional forces that oppose its motion. The type of friction that acts depends on the nature of the surfaces in contact and the motion involved.

3. **Determine the Type of Friction**:
- Since the book is on cylindrical pencils, the pencils can roll.
- When an object rolls over a surface, the friction that acts is known as **rolling friction**.

4. **Direction of Friction**:
- If the book is pushed in one direction, the rolling friction will act in the opposite direction to resist the motion of the book.

5. **Conclusion**: Therefore, the type of friction that comes into play when a book kept on cylindrical pencils is moved by pushing is **rolling friction**.

### Final Answer:
The type of friction is **rolling friction**.

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