A force acting perpendicular to two surfaces in contact with each other. It is a measure of the force holding the two surfaces together. The larger the normal reaction force, the larger the value of limiting friction. If weight is the only vertical force acting on an object lying or moving on a horizontal surface, the normal reaction force is equal in magnitude, but opposite in direction to the weight. Friction, therefore, is increased by increasing the weight.
normal reaction force
Subjects: Sports and Exercise Medicine.