When a box is at rest on a level floor, forces are exerted between the atoms in the bottom surface of the box and atoms in the top surface of the floor. Why does the floor not exert a frictional force on the box?
A) The force exerted between any atom in the floor, and any atom in the box is always vertical, leading to a normal force but not a frictional force.
B) The force is exerted between atoms are equal in magnitude and opposite in direction, so the net force between the box and floor is zero.
C) The horizontal component of the force exerted between any atom in the floor, and any atom in the box is always negligible compared to the vertical component of the force.
D) The horizontal component of the force is exerted between atoms in the floor and atoms in the box are not negligible but sum to zero.