A Contact force is a force applied to a body by another body that is in contact with it. Contact force acts on a point of direct contact between the two objects. This force can either be continuous as a continuous force or can be momentary in the form of an impulse. Contact force is governed by Newton’s Laws.
Examples :: Contact force is responsible for most of the interactions we experience in the daily life.
1. Writing your name with a pen, pushing a car up a hill, lifting an object, etc...
2. Kicking a ball, hammering a nail, etc...
are some of the everyday examples where contact forces are at work.
In the first case, the force is continuously applied by the person on the car or pen or an object while in the second case the force is delivered in a short impulse.
Contact forces are often decomposed into orthogonal components
one perpendicular to the surface in contact called the normal force, and
one parallel to the surface in contact, called the friction force.