Determine the maximum stable slope of granular materials.
Pile Parameters
Calculation Results
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About this calculator
Quick Reference
θAngle of Repose
hHeight
rRadius
μsCoefficient of Static Friction
Overview
The angle of repose is the steepest angle of descent or dip relative to the horizontal plane to which a granular material can be piled without slumping.
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Pro Tips
Smooth, rounded grains have a lower angle of repose than irregular, interlocking grains.
Small amounts of moisture (like in a sandcastle) can increase the angle significantly due to surface tension.
Vibrations or additional weight can cause a pile to collapse even if it's below the theoretical angle of repose.
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Fun Facts
"The 'singing sands' phenomenon usually occurs in dunes where the sand is at its critical angle of repose."
"Antlions use the angle of repose to their advantage by digging conical pits in dry sand; if an ant steps in, the sand slides, trapping the prey."
"Mountains and volcanoes also have an effective angle of repose, which determines their characteristic shapes."
