Static Friction Formula

Let us imagine a car at rest. To start it without making use of the accelerator, one will have to use a lot of force.


This is static friction! Here the object at rest is made to move to conflict the frictional force.

Static friction is the resistive force perceived in a body that is at rest. It is articulated as

\(\begin{array}{l}F_{s}= \mu _{s}F_{n}\end{array} \)


  • static friction is Fs
  • the coefficient of static friction is μs
  • the normal force is Fn

Static Friction Formula helps one to compute the frictional force, coefficient of friction, or normal force in any asked numerical.

Static Friction Solved Examples

Underneath are numerical on static friction which helps to comprehend where one can use this formula:

Problem 1: A force of 200 N is exerted on a snack box of 5 kg still on the floor. If the coefficient of friction is 0.3, calculate the static friction.


Fn (Normal force) = 200 N,
μs  (Coefficient of friction) = 0.3,
Static friction is given by Fs =μs  Fn
= 0.3 × 200 N
F= 60 N.

Problem 2: Amy is hauling a toy car of mass 4 kg which was at rest earlier on the floor. If 50 N is the value of the static frictional force, calculate the friction coefficient?


m (Mass) = 4 kg,
Fs  (static frictional force) = 50 N,
Fn (Normal force) = mg
= 4 Kg × 9.8 m/s2
Fn= 39 N

μs = Fs /Fn

μs = 50/39

μs  = 1.282

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