The free surface shape of a bucket of sand rotating about its cylindrical axis is studied both theoretically and experimentally. The experimental surface shape is found to depend on the material’s angle of internal friction and the imposed rotation rate, and provides a way of experimentally measuring the angle of internal friction. The results may be approximated by a theory which assumes that the surface deforms according to the Coulomb yield condition. The results are compared with the surface of a spinning bucket of water.

DOI:https://doi.org/10.1103/PhysRevE.50.R3353