 # Difference between Kinetic Friction and Static Friction Do you know what the difference is between kinetic friction and static friction? If not, you’re not alone! A lot of people don’t know the difference, but it’s actually pretty interesting. Kinetic friction is the force that resists when two objects are moving against each other. Static friction, on the other hand, resists when two objects are stationary with respect to each other.

So, now you might be wondering which one is stronger – kinetic or static friction? The answer: static friction is always stronger than kinetic friction. In fact, kinetic friction can be completely eliminated if there is enough static friction present. Check out this post to learn more about the difference between kinetic and static friction!

Contents

## What is Kinetic Friction?

• Kinetic friction is the force that opposes the motion of two surfaces in contact. The amount of kinetic friction depends on the nature of the surfaces in contact, with rougher surfaces experiencing more friction than smoother ones.
• Kinetic friction also depends on the force with which the surfaces are pressed together. In general, the larger the force, the greater the amount of kinetic friction. Kinetic friction is what makes it difficult to start a moving object, and also what makes it difficult to keep a moving object moving at a constant speed.
• Kinetic friction is caused by the interaction of atoms on the surface of the materials in contact. When two surfaces are pressed together, the atoms on one surface become interlocked with the atoms on the other surface. This interlocking creates a resistance to motion, which we experience as kinetic friction.

## What is Static Friction?

Static friction is a force that prevents two surfaces from sliding past each other. Static friction is also known as stiction or limiting friction. Static friction occurs when an object is at rest or is being accelerated. The force causes the object to move at a constant velocity.

• Static friction is greater than kinetic friction. The amount of static friction depends on the type of surfaces in contact, the angle between the surfaces, and the normal force. Static friction is caused by irregularities in the surface of the object.
• The irregularities cause an adhesive force between the object and the surface. The object will not move unless enough force is applied to overcome the static friction. Static friction can be useful, such as when you are holding an object in your hand.
• Static friction can also be a nuisance, such as when you are trying to slide a heavy object across a floor. Static friction can be overcome by increasing the force or by changing the surfaces in contact.

## Difference between Kinetic Friction and Static Friction

Kinetic friction is the force that opposes the motion of objects that are already in motion. Static friction is the force that opposes the motion of objects that are not in motion. Kinetic friction is caused by the unevenness of surfaces and the imperfections of surfaces in contact with each other.

• Static friction is caused by the interaction of different kinds of molecules on the surface of an object. Kinetic friction is always less than static friction.
• The coefficient of static friction is usually greater than the coefficient of kinetic friction. The difference between static friction and kinetic friction can be explained by looking at how these types of frictional force are generated.
• Kinetic friction is created by the irregularities of surfaces in contact with each other while static friction us generated by the interlocking of molecules on different surfaces.
• The amount of force needed to overcome static friction is greater than the amount of force needed to overcome kinetic friction because it takes more energy to overcome the interlocking of molecules than it does to overcome the irregularities of surfaces.
• When an object is being pushed or pulled, there is always a resistive force, called friction, that acts against the direction of motion. The faster an object moves, the greater this resistive force becomes.

This happens because there are more molecules in contact with each other when an object moves faster and thus there is more resistance to motion. The resistive force also depends on how slippery the surfaces that are in contact with each other – a very smooth surface will have less resistive force than a rough surface.

## Conclusion

Kinetic friction is the force that resists an object’s motion when two surfaces are in contact. Static friction is the force that resists an object’s motion when two surfaces are not in contact.