What is the Difference Between Static friction and Kinetic friction?

The main difference between static friction and kinetic friction lies in the movement of the objects in contact with each other. Static friction opposes the impending motion of objects, while kinetic friction opposes the relative motion of objects that are already in motion. Here are some key differences between the two:

Static Friction: This type of friction is experienced when an object is placed on a surface and opposes the impending motion. It is proportional and perpendicular to the normal force and depends on the nature of the surface in contact. Static friction is independent of the area of contact and the coefficient of static friction is generally greater than the coefficient of kinetic friction. Some examples of static friction include a pen placed on a tabletop or a stationary vehicle on the road.
Kinetic Friction: This type of friction is due to the movement of an object on a surface and opposes the relative motion of the object. Kinetic friction is independent of velocity and depends on the nature of the surface in contact. The coefficient of kinetic friction (μk) is generally less than the coefficient of static friction (μs) for the same materials. Examples of kinetic friction include sliding a box on the floor or the movement of a vehicle on the road.

In summary, static friction prevents objects from moving when they are at rest, while kinetic friction acts on objects that are already in motion. The coefficient of static friction is generally greater than the coefficient of kinetic friction, and the two types of friction depend on the nature of the surfaces in contact.

On this page

What is the Difference Between Static friction and Kinetic friction?

Comparative Table: Static friction vs Kinetic friction

Here is a table comparing static friction and kinetic friction:

Property	Static Friction	Kinetic Friction
Definition	Static friction is the force that opposes the impending motion between two objects in contact when there is no actual relative motion between them.	Kinetic friction is the force that opposes the relative motion between two objects in contact when they are already in motion.
Coefficient	The coefficient of static friction (μs) is generally higher than the coefficient of kinetic friction (μk) for the same materials.	The coefficient of kinetic friction (μk) is generally lower than the coefficient of static friction (μs) for the same materials.
Direction	Static friction acts in the opposite direction to the impending motion, preventing the objects from moving.	Kinetic friction acts in the opposite direction to the relative motion between the objects, opposing their motion.
Applications	Examples of static friction include a pen placed on a tabletop, a chair on a floor, or a stationary vehicle on the road.	Examples of kinetic friction include sliding a box on the floor, the movement of a vehicle on the road, or writing on a blackboard with chalk.
Dependence on Speed	Static friction does not depend on the speed of the objects.	Kinetic friction depends on the speed of the objects in contact.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.