Difference Between Static Friction and Kinetic Friction

Main Difference

Friction is one of the most important forces that are held responsible for movement on the surface of Earth or in other words we can say that indirectly this is the force which has made the life possible on Earth. As a common mindset, we know that friction is the resisting force that is always available when two or more than two bodies collide. In easy words, friction is the force that works as a hindrance or as opposed to the motion of the object. There are four major types of friction, static friction, kinetic friction, rolling friction and fluid friction. Static Friction is the type of friction between the bodies which keeps the object at rest, whereas when the force acting against friction overcomes static friction and body comes in motion, kinetic friction is the type of friction which slows down the moving object. The magnitude of static friction is always more than the kinetic friction. It means that more force is required to overcome the static friction or to make the object move than in the kinetic friction where the force applied is to make object keep moving as it is already in motion.

Comparison Chart

Static FrictionKinetic Friction
DefinitionStatic Friction is the type of friction between the bodies which keeps the object at rest.When the force acting against friction overcomes static friction and body comes in motion, kinetic friction is the type of friction which slows down the moving object.
Formula/EquationFk = μk ηFsmax = μs η
MagnitudeThe magnitude of static friction is greater due to the greater value of its coefficient.The magnitude of kinetic friction is less as compared to static friction, due to the less value of its coefficient.
OthersValue static friction does not change so often and remain constant.Value of kinetic friction keeps on fluctuating due to the continuous motion of the bodies.

What is Static Friction?

It is the type of friction between the bodies which keeps the object at rest. When you apply a force on the table to drag it and fail several times, the force making you fail all these times is the static friction as it works as the opposer or the antagonist of the motion. To beat or cut off this static friction, what you do is that you put in more of your force, and finally, the table gets moving. When the objects on the rest start moving, that means static friction has reached its maximum value. If an object is in the state of rest and no external force is acting upon against it to make it in the motion, the static friction is zero as much the external force increases the static friction increases, and at one stage the static friction reaches its maximum value and objects starts moving. The static friction depends upon μsμs (coefficient of static friction) and N (net normal reaction of the body). The static friction can either be less or equal to the product of μsμs (coefficient of static friction) and N (net normal reaction of the body). The static friction is exactly equal to the external force being put on the object and is always opposite to the direction of motion.

What is Kinetic Friction?

When a body comes in motion after overcoming the static friction or the static friction reaches its maximum value, the force which works as opposed and slows down the moving object is called the kinetic friction. The magnitude of kinetic friction is low as compare to the magnitude of static friction that is why it works as a hindrance in between the object but didn’t put it to the rest state it just slows down the motion of the moving object. When you apply a force on the table to drag it and fail several times, the force making you fail all these times is the static friction as it works as the opposer or the antagonist of the motion. To beat or cut off this static friction, what you do is that you put in more of your force, and finally, the table gets moving, and when you try to drag the table more quickly, you will feel a certain force working as a hindrance and slowing it down. The force acting at that time will be the kinetic friction. The formula for Magnitude of kinetic frictional force fk = μkμk N, where μkμk is the coefficient of kinetic frictional force, and N is the net normal reaction on the body.

Key Differences

  1. Static friction is the force of friction acting between the surfaces of two bodies that are in the rest position i.e. not moving.
  2. Kinetic friction is the kind of force of friction, that acts between the surfaces of two bodies that are in continuous motion.
  3. The value of static friction does not change.
  4. The value of kinetic friction keeps on changing as the objects are in motion.
  5. Static friction needs to be reduced or overcome in order to move an object.
  6. Kinetic friction is the force of resistance between the objects moving against each other.
  7. Static friction coefficient is greater than Kinetic friction coefficient.

Comparison Video

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Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss

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