Question

Define normal reaction

Answer 1

The force exerted by a surface on an object in contact with it which prevents the object from passing through the surface; the force is perpendicular to the surface, and is the only force that the surface exerts on the object in the absence of frictional forces.

Answer 2

Explanation:

A force acting perpendicular to two surfaces in contact with each other. ... 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.