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Friction Formula

Friction is unavoidable in our day-to-day lives. Man keeps trying so many techniques to reduce friction in any process, but he also realises that without friction none of his work would have been possible. Life would have been impossible without the aid of friction. Yet friction is termed as an evil. Without friction one can't walk, write, sit on a chair without slipping off or for that matter, even properly hold on to his or her morning cup of tea.

Friction is the retarding force coming into play when two bodies are in contact with each other.
Friction Formula
Friction formula in general is given by

Ff is the magnitude of friction,
$\mu$ is the coefficient of friction and
Fn is the magnitude of normal force.

The Normal force = Weight of the given body. Hence Normal force Fn is given by

m is the mass of the body and 
g is the gravity.

Friction formula is used to calculate the friction between the any two given bodies.

Related Calculators
Friction Calculator Calculate Kinetic Friction
Calculate Static Friction Friction Loss Calculator

Friction Problems

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Below are problems on friction which helps to know where the formula can be used:

Solved Examples

Question 1: A boy is pulling box of mass 10 Kg. What is the normal force acting and also find the frictional force if the coefficient of friction $\mu$ is 0.3?
Given: Mass, m = 10 Kg,
          Normal force, Fn =?
Normal force is given by Fn = mg
                                        = 10 Kg $\times$ 9.8 m/s2
                                        = 98 N.
The Frictional force is given by Ff = $\mu$ Fn
                                                 = 0.3 $\times$ 98 N.
                                                 = 29.4 N.


Question 2: Nancy is of mass 40 Kg is sliding on the ice. If the coefficient of friction acting is 0.45. Find the frictional force acting between her and ice layer?
Given: Mass m = 40 Kg,
Coefficient of friction $\mu$ = 0.3,
The Normal force is given by Fn = mg
                                              = 40 Kg $\times$ 9.8 m/s2
                                              = 392 N.
The Frictional force is given by Ff = $\mu$ Fn
                                                 = 0.45 $\times$ 392 N
                                                 = 176.4 N.


More topics in Friction Formula
Kinetic Friction Formula Static Friction Formula
Friction Loss Formula Friction Force Formula
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