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Friction Force from Contact Load & Coefficient

Find kinetic friction or the limiting static friction from a coefficient and the normal contact force.

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Enter the known values in the units shown. Results update as you type.
Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
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With normal force 100 N and coefficient 0.3, kinetic friction or the maximum static friction is 30 N.

Friction magnitude = coefficient × normal contact force

Enter these known values and leave the other values blank.

Use the kinetic coefficient for sliding contact. With a static coefficient, the result is the upper bound before slipping, not necessarily the actual static force.
Normal force is positive and acts perpendicular to the contact surface. It equals weight only in appropriate geometries and force balances.
Coefficient and friction magnitude are nonnegative; coefficients can exceed one. This simple dry-friction model does not include speed, wear or temperature dependence.

Static friction adjusts to balance the tangential load up to its limit. Multiplying the static coefficient by normal force gives that limit.

It calculates magnitude. Sliding friction acts opposite relative sliding at the contact.

The pound-force uses the exact international pound and standard gravity instead of the rounded captured factor.