Practical tools for measured work
Friction calculator
Distinguish actual static friction, maximum static friction and kinetic friction, or solve a coefficient.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
The block remains at rest: actual static friction balances the applied force.
How it works
Static friction adjusts to oppose the applied force up to μsN; it is not always equal to that maximum. Once the static limit is exceeded, this initially-resting-block model uses kinetic magnitude μkN. For N = 100 N and μs = 0.5, a 20 N push is balanced by 20 N static friction, not 50 N.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Friction calculation
- Initially resting block
- Normal force
- 100 N
- Static friction coefficient
- 0.5
- Kinetic friction coefficient
- 0.3
- Signed applied horizontal force
- 20 N
Primary result: Signed friction force: -20 N.
Before using the result
- Check the selected mode, units and input values before using the result.
- Read the assumptions and rounding rules; compare the worked example with your intended calculation.
- A numerical result does not supply missing context or change the stated limitations.
Limitations
Horizontal block initially at rest, with supplied normal force and nonnegative coefficients. The sliding direction is inferred from the applied force. Already-moving objects, rolling resistance and complex contact behaviour need a different model.
Frequently asked questions
Which physical model does this result assume?
Use only the configuration named in the selected mode. Enter consistent SI units and check the stated direction, axis and equilibrium assumptions. These educational ideal models do not certify equipment, structures or lifting arrangements.
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