51 research outputs found
Rolling friction of a viscous sphere on a hard plane
A first-principle continuum-mechanics expression for the rolling friction
coefficient is obtained for the rolling motion of a viscoelastic sphere on a
hard plane. It relates the friction coefficient to the viscous and elastic
constants of the sphere material. The relation obtained refers to the case when
the deformation of the sphere is small, the velocity of the sphere is
much less than the speed of sound in the material and when the characteristic
time is much larger than the dissipative relaxation times of the
viscoelastic material. To our knowledge this is the first ``first-principle''
expression of the rolling friction coefficient which does not contain empirical
parameters.Comment: 6 pages, 2 figure
The prevalence and risk indicators of tooth wear in 12- and 15-year-old adolescents in Central China
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