Contact force- forces acting by direct contact between the bodies, for example, frictional force (it cannot act without contact) as well as muscular force.

Classification of Forces:
1. Contact Forces:
Contact forces are those forces that act between two objects that are in direct physical contact with each other. These forces require the objects to be touching for the force to be exerted.
Example:
- Normal Force: This force acts perpendicular to the surface of an object and prevents objects from passing through each other. For example, when you sit on a chair, the normal force exerted by the chair supports your weight and prevents you from falling through.
2. Non-Contact Forces:
Non-contact forces are those forces that act between objects that are not in direct physical contact with each other. These forces can act over a distance without the need for physical contact between the objects.
Example:
- Gravitational Force: This force acts between any two objects with mass and is responsible for the attraction between objects. For example, the gravitational force between the Earth and objects on its surface keeps us grounded.
Understanding the classification of forces is essential in physics as it helps us analyze and predict the interactions between objects in different situations. By recognizing whether a force is contact or non-contact, we can better understand how objects move and interact with each other in the physical world.