The force of kinetic friction, **also called stop** or resisting force, is the resistance of a **body moving across** a surface surface to relative movement in the opposite direction.

Kinetic friction is based on the roughness of the surfaces in contact and the velocity of the body relative to the surface. The greater the velocity and roughness of the surfaces, the greater kinetic friction.

The coefficient of kinetic friction, **also called coefficient** of sliding or simply coefficient of friction, is a scalar value that is determined by experiments to **quantify kinetic frictional forces**. It is always dimensionless, with a value between 0 and 1 depending on which side of 1 it is on.

There are many ways to find the coefficient of kinetic friction between two surfaces. Experiment with different methods to find which ones are most accurate.

## Calculate the area of friction for block a

To calculate the coefficient of kinetic friction, you *must first calculate* the area of friction between the two objects. The area of friction is determined by finding how **much surface area** of the block is in contact with the table.

To do this, first find the * total surface area* of the block by dividing its length by two and multiplying that number by its width. Then, find how much of that surface area is in contact with the table by tracing around the bottom side of the block on the table top.

This is just a matter of tracing around the edges of the block on top of each other to find how big it is, then subtracting that size from the total surface area to find how much comes out as being on the table.

## Calculate the weight of block b

Now that you have calculated the force of gravity on the block, you can calculate the weight of the block. The weight of an object is calculated by multiplying its mass by the **gravitational field strength**.

To calculate the mass of the block, you need to find out how much it weighs and what kind of material it is made of. You already found out how much it weighs, so now you need to find out what type of material it is made of.

To do this, you will use a *method called tapping* and knocking. This means that you will tap or knock on the block and listen to the sound it makes. If the sound is solid, then the block is probably solid as well.

However, if it *sounds hollow*, then it is **probably hollow** as well.

## Calculate the area of friction for block b

To calculate the coefficient of kinetic friction, you must first calculate the area of friction between the two objects. The area of friction is calculated by subtracting the *total surface area* of the top object from the total surface area of the bottom object.

In this case, we have a rectangular block on a rectangular table top, so we can use some math to figure out the area of friction.

First, convert both dimensions from centimeters to meters to *make things easier* when you do the calculations. Then, take the length of the block and divide it by two, then take the length of the table top and divide it by two. You will get similar numbers for each dimension–these are just different dimensions of one object. Add these numbers together to get your total surface area of just this object.

Now, subtract this from one object’s surface area to get just the surface area of just this object.

## Compare your results with those presented in the article

The coefficient of kinetic friction, μ, is a number that represents the effectiveness of friction between two surfaces. Friction is a force that acts to resist the motion of **one object relative** to another.

There are two types of friction: static and kinetic. Static friction is the resistance to initial movement, while kinetic friction is the resistance to continued movement. Both are present in everyday situations where **objects encounter one another**.

When you try to slide a book across a table, for example, there is static friction that keeps the book planted on the table until you **apply enough force** to move it. If you apply enough force, then there is also kinetic friction that stops the book from sliding any further.

You can actually test for these **frictions experimentally using devices called pendulums** and chronometers.

## Kinetic friction is a force that acts on two moving surfaces when they are touching

Kinetic friction is *also called walking friction*. If you walk on a smooth surface, your foot will slide slightly on the surface before coming to a stop.

This is because of the kinetic friction between your foot and the surface. The greater the thickness of the surface, the greater the kinetic friction.

The coefficient of *kinetic friction tells* you how *much static friction changes due* to kinetic (moving) friction. A coefficient of 0 means that there is no change, and 1 means that there is total change.

For example, if you have a thick mat on your floor, then you have more static frictions than if you had a thin floor coverings. A **thicker mat would** have more static frictions than if it was thin.

Kinetic friction depends on the moving surfaces and their velocity relative to each other.