Kinetic Friction

Nov 21, 2022, 16:45 IST

Kinetic friction is defined as the force that acts between moving surfaces. A body moving on a surface is subjected to a force in the opposite direction of its movement. The magnitude of the force will also depend on the coefficient of the kinetic friction between the two given materials.

Table of Content
What is Kinetic Friction? Formula of Kinetic Friction Types of Friction Applications of Kinetic Friction Frequently Asked Questions (FAQs)

What is Kinetic Friction?

A friction can be easily defined as the force that holds a sliding object back. Kinetic friction is part of everything and disrupts the motion of two or more objects. The force acts opposite to the direction in which the object wants to slide. If the car has to stop, we apply the brakes, and that's exactly where the friction comes into play. When walking, when one wants to stop suddenly, the friction is to thank again. When we have to stop in the middle of a puddle, the things are more difficult because there is less friction, and it can't help us as much.

Formula of Kinetic Friction

The coefficient of kinetic friction is represented by the Greek letter "mu" (μ) with a subscript "k." The force of kinetic friction is μk times than the normal force acting on the body. It is expressed in Newtons (N). The kinetic friction equation can be written as-

Force of kinetic friction = (coefficient of kinetic friction) x (normal force)

Fk= μk.η

Types of Friction

There are two types of friction which are given below-

Kinetic Friction
Static Friction

Static friction is the friction between the two given objects that are not moving relative to each other. In liquids, the frictional resistance between moving layers of liquid is better known as viscosity. Now take two moving solid objects, this is known as moving or kinetic friction because of its motion.

This friction is a special fraction of the perpendicular force acting between two bodies. The coefficient of friction determines the fraction, which in turn, is determined through experiments. The force is independent of the area of contact and does not change regardless of how fast the two objects are moving. While in contrast, static friction is what affects stationary objects. The force of the friction is the force that prevents motion when two objects are in contact. If you look at the surfaces of all the objects, there are tiny bumps and ridges. These microscopic peaks and valleys lock onto each other as the two objects move past each other. Of course, there are other forces at work, such as chemical bonding and electrical interactions.

Applications of Kinetic Friction

Friction also plays an important role in everyday events, such as two objects rubbing together. The resulting movement is converted into heat, which in some cases leads to a fire.
It is also responsible for wear, and hence we need oil to lubricate machine parts as it reduces friction.
When the two objects rub against each other, the frictional force is converted into heat energy, which in several cases leads to fire.
Kinetic friction is responsible for the wear of machine parts, so it is important to lubricate machine parts with oil.