A boy presses a book against the front wall such that the book does not move. The force of friction between the wall and the book is

Options

A. Towards right
B. Towards left
C. Downwards
D. Upwards

Explanation

To solve the problem regarding the force of friction between the wall and the book, we can follow these steps:

### Step 1: Identify the Forces Acting on the Book
When the boy presses the book against the wall, several forces act on it:
- The gravitational force (weight) acting downward.
- The normal force exerted by the wall on the book acting horizontally.
- The frictional force acting between the wall and the book.

### Step 2: Understand the Role of Friction
Friction acts to oppose the relative motion between two surfaces in contact. In this case, since the book is pressed against the wall and does not move, the frictional force must be sufficient to counteract any forces trying to slide the book down.

### Step 3: Analyze the Directions of Forces
- The gravitational force (weight) acts downward.
- The normal force from the wall acts horizontally (perpendicular to the wall).
- The frictional force acts in the opposite direction to the gravitational force to prevent the book from sliding down.

### Step 4: Conclude the Direction of the Frictional Force
Since the gravitational force pulls the book downwards, the frictional force must act upwards to balance this force and keep the book stationary against the wall.

### Step 5: State the Force of Friction
Thus, the force of friction between the wall and the book acts in the upward direction.

### Final Answer
The force of friction between the wall and the book is directed upward.

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