The maximum frictional force between two bodies is proportional to what factors?

The maximum frictional force between two bodies is proportional to the resultant of all forces that are perpendicular (normal forces) to the surfaces in contact. This relationship is defined by the equation of friction, which states that the frictional force can be calculated by the coefficient of friction multiplied by the normal force. The normal force is a crucial factor because it dictates how tightly the two surfaces are pressed together; a greater normal force results in greater friction.

Factors such as the product of masses, the velocity of the moving body, or the area of contact contribute to friction but do not define its maximum value as clearly as the normal forces do. For instance, while mass plays a role in the normal force (as weight is the product of mass and gravitational acceleration), it is the actual force that is perpendicular to the contact surface that determines the frictional force. Similarly, the velocity of a body can affect friction in dynamic situations, but it does not directly influence the maximum static frictional force. The area of contact can affect frictional resistance but does not proportionally relate to maximum frictional force, as long as the surfaces are rough enough to maintain the same pressure.

Thus, the correct answer highlights the importance of the normal force in establishing the extent of friction