What is Forces? Reaction or Normal force - Law of Motion

Forces

Reaction  or Normal  force:

 

When  a body  is placed  on a rigid  surface, the body  experiences a force which  is perpendicular to the surfaces in  contact. Then force is called ‘Normal  force’ or ‘Reaction’. 

Symbol of normal force (N) and (R)

 

Normal force in horizontal surface: When a body lies on a horizontal surface N= mg.