Friction Calculator

The Friction Equation

The friction force is calculated using the equation:

f = μN

Variables in the Friction Equation

• f = friction force, in newtons (N)
• μ = coefficient of friction (unitless)
• N = normal force, in newtons (N)

Friction Formulas

Depending on which values you know, you can calculate the unknown variable:

Calculate Friction Force (f)

Given coefficient of friction (μ) and normal force (N):

f = μN

Calculate Coefficient of Friction (μ)

Given friction force (f) and normal force (N):

μ = f/N

Calculate Normal Force (N)

Given friction force (f) and coefficient of friction (μ):

N = f/μ

Normal Force from Mass and Gravity

If you know the mass of an object and the gravitational acceleration, you can calculate the normal force:

N = mg

Where:

• m = mass, in kilograms (kg)
• g = gravity, in meters per second squared (m/s²)

Types of Friction

Static friction occurs when two surfaces are not moving relative to each other.

Kinetic friction occurs when two surfaces are sliding against each other.