You can keep a 3 kg book from dropping by pushing it horizontally against a wall. What force must you apply to the book to keep it from falling? What is the coefficient of static friction?

x: F= N

y: mg=F(fr)

mg=F(fr) =μ•N= μ•F
F=mg/ μ

To determine the force required to keep the 3 kg book from falling, we need to consider the forces acting on the book. In this scenario, there are two forces at play:

1. Force of gravity (Weight): The weight of the book is equal to its mass multiplied by the acceleration due to gravity (9.8 m/s^2). Therefore, the weight of the book is given by: Weight = mass x gravity = 3 kg x 9.8 m/s^2 = 29.4 N (Newtons).

2. Force of friction: The force of static friction opposes the tendency of the book to slide down the wall. In this case, it acts horizontally from the wall to the book.

To keep the book from falling, the applied force must be equal in magnitude but opposite in direction to the force of static friction, so that the net force would be zero.

Therefore, the force you need to apply to the book to keep it from falling is equal to the force of static friction, which can be determined using the following equation:

Force of static friction = coefficient of static friction x normal force

Here, the normal force refers to the force exerted by the wall on the book perpendicular to its surface. In this case, since the book is resting against the wall, the normal force is equal in magnitude to the weight of the book (29.4 N).

Hence, the force you need to apply to the book to keep it from falling is the same as the force of static friction, which can be found by multiplying the coefficient of static friction and the normal force (weight).

However, the coefficient of static friction is not provided in the given information, so we cannot calculate the actual force without additional details. We would need to know the coefficient of static friction between the book and the wall to calculate the force needed to keep it from falling.