# What are the equations to calculate friction

• ellomoto135
In summary, the equations for calculating friction depend on whether the surfaces are stationary, moving, or about to move. If they are stationary or moving, the friction force is equal to the coefficient of friction (µ) multiplied by the normal force (N). If they are about to move, the friction force is equal to the static coefficient of friction (µs) multiplied by the normal force. The values for µ and µs can be found in a table or given in an exam question.
ellomoto135
What are the equations that can be used to calculate friction, be detailed i don't know much about.

welcome to pf!

hi ellomoto135! welcome to pf!

there isn't much to say …

if the surfaces aren't moving, and aren't "about to move", the friction force is simply part of the reaction force … you calculate it exactly as if the surfaces were fixed together

if they are moving, you have to look up the kinetic (dynamic) coefficient of friction, µk, in a table (or it'll be given in an exam question), and then
the friction force is µkN (where N is the normal force)

if they are "about to move", you have to look up the static coefficient of friction, µs, in a table (or it'll be given in an exam question), and then
the friction force is µsN (where N is the normal force)

## 1. What is the equation for calculating friction?

The equation for calculating friction is F = μN, where F is the force of friction, μ is the coefficient of friction, and N is the normal force.

## 2. How do you calculate the coefficient of friction?

The coefficient of friction can be calculated by dividing the force of friction by the normal force.

## 3. What is the normal force in a friction equation?

The normal force is the force that is perpendicular to the surface of contact between two objects. It is equal to the weight of the object pressing down on the surface.

## 4. How does surface area affect friction?

Surface area does not directly affect friction. However, it can indirectly affect it by increasing the number of contact points between two surfaces, which can increase the coefficient of friction.

## 5. Can the coefficient of friction be greater than 1?

Yes, the coefficient of friction can be greater than 1, which indicates a higher frictional force between two surfaces. This can occur with rough or sticky surfaces, for example.

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