**Friction Force Formula**

Friction is a repelling force when one body is slipping through a surface. Friction is because of the contact between two surfaces. If frictional force is great, the movement of objects through the surface is not in a smooth manner. All through this movement, the kinetic energy is transformed to heat energy.Â **FrictionÂ **force is a derived force and not like gravitation i.e. a fundamental force. The formula for friction force is,

WhereÂ F_{f}Â is the friction, Î¼Â is the coefficient of friction forceÂ andÂ F_{n}Â is the normal force. It is a vector quantity.

**Friction Force – Solved Examples**

Let us answer some problems about friction force.

**ProblemÂ 1:Â **An object of mass 10kg is moving through a surface. Compute the friction force if the coefficient of friction is 0.2?

**Answer:**

Known variables are,

m = 10kg andÂ Î¼Â = 0.2

Friction force formula is,

F_{f}Â =Â Î¼F_{n}

FnÂ can be computed as,

FnÂ = mg

= 10Ã—9.81 = 98.1N

So, F_{f}Â = 0.2Ã—98.1 = 19.62N

**ProblemÂ 2:Â **Calculate the friction force of a 5kg body which is moving through a surface with a friction coefficient 0.3?

**Answer:**

Known variables are,

m = 5kg andÂ Î¼Â = 0.3

Friction force formula is,

F_{f}Â =Â Î¼F_{n}

F_{n}Â can be computed as,

F_{n}Â = mg

= 5Ã—9.81 = 49.05N

So, FfÂ = 0.3Ã—49.05 = 14.715N