friction is a contact force because to follow this statement friction is a force that opposes relative motion between the two surfaces of objects in contact. this statement tell us that friction take place when two surfaces of object in contact take some examples over here when we push a box on the so the box is sliding over the surface of another body as you can see friction take place and object at that time stop you observe that when one object is in contact with another object then the frictional force takes place hence,it is proved that frictional force is a contact force.

Introduction:

Friction is a force that opposes the motion of an object when it comes into contact with another object or surface. It is a contact force because it only occurs when two objects are in direct contact with each other. Friction plays a crucial role in our everyday lives and is responsible for various phenomena such as walking, driving, and even holding objects.

Explanation:

1. Definition of friction:
Friction can be defined as the force that resists the relative motion or tendency of motion between two surfaces in contact. It acts in the opposite direction to the applied force or the direction of impending motion.

2. Microscopic explanation:
Friction is a result of the interaction between the irregularities present on the surfaces of objects in contact. When two surfaces come into contact, the microscopic roughness of these surfaces interlocks with each other. As a result, a resistance force is generated that opposes the motion or attempted motion between the objects.

3. Types of friction:
There are three main types of friction:
- Static friction: This type of friction occurs when an object is at rest and an external force is applied to move it. The static friction force prevents the object from moving until the applied force overcomes it.
- Sliding friction: Sliding friction occurs when two objects slide or move relative to each other. It is generally weaker than static friction.
- Rolling friction: Rolling friction is experienced by objects that roll over a surface, such as a ball rolling on the ground. It is usually the weakest type of friction.

4. Importance of contact:
Friction is a contact force because it requires direct physical contact between two objects or surfaces. The interaction between the surfaces allows for the interlocking of microscopic irregularities, which leads to the generation of frictional forces.

5. Surface characteristics:
The amount of friction depends on the nature and characteristics of the surfaces in contact. Smooth surfaces have less interlocking and thus less friction, while rough surfaces create more interlocking and result in higher friction.

6. Limiting friction:
There is a maximum value of friction known as the limiting friction. Once the applied force exceeds this limit, the object will start to move. The limiting friction depends on the nature of the surfaces and the normal force between them.

Conclusion:
Friction is a contact force that occurs when two objects or surfaces come into direct physical contact with each other. It is a result of the interlocking of microscopic irregularities and plays a significant role in our daily activities. Understanding friction helps in designing efficient machines, improving traction, and ensuring safety in various applications.