Moffatt (Nature 404, 833 - 834) discusses the ever-intriguing motions of a rolling disk, as it whirrs and shudders to a horizontal stop
نویسنده
چکیده
Regarding generality, the paper does not apply to the two examples mentioned, coins and a toy (Fig. 2 therein) by lack of the conformal contact that the theory demands (Fig. 1 therein): a coin by its raised images and generally rough edges, and the toy by its concave support bowl (Fig. 2 of the paper). One can roll almost any disk, including the toy and a coin, on a variety of nominally flat surfaces and note that the settling time differs by factors of two or so (although the disk parameters and air viscosity vary by far less than 1% between observations). Thus the viscous mechanism can't generally be the primary damping.
منابع مشابه
The rolling of a disk on a horizontal plane: II. Euler’s disk
This paper continues the study of a disk rolling on a horizontal plane. In this Part we focus our efforts on the nonlinear oscillations about the equilibria, appropriate to modelling the later stages of the Euler disk motions, when the disk is nearly horizontal.
متن کاملMotions of a Rimless Spoked Wheel: a Simple 3D System with Impacts
This paper discusses the mechanics of a rigid rimless spoked wheel, or regular polygon, ‘rolling’ downhill. By rolling, we mean motions in which the wheel pivots on one ‘support’ spoke until another spoke collides with the ground, followed by transfer of support to that spoke, and so on. We carry out three-dimensional numerical and analytical stability studies of steady motions of this system. ...
متن کاملSteady Motion of a Rigid Disk of Finite Thickness on a Horizontal Plane
The article discusses the steady motion of a rigid disk of finite thickness rolling on its edge on a horizontal plane under the influence of gravity. The governing equations are presented and two cases allowing for a steady state solution are considered: rolling on consistently rough ground and rolling on perfectly smooth ground. The conditions of steady motion are derived for both kinds of gro...
متن کاملJames Bond and Global Health Diplomacy
In the 21st Century, distinctions and boundaries between global health, international politics, and the broader interests of the global community are harder to define and enforce than ever before. As a result, global health workers, leaders, and institutions face pressing questions around the nature and extent of their involvement with non-health endeavors, including international conflict reso...
متن کاملNumerical and Experimental Analysis of Forming Rectangular Copper Pipes by Successive Rolling of Round Pipe Filled With Bismuth
Because of their wide application in industries requiring high pressure and temperature, manufacturing square and rectangular pipes have attracted more attention than ever before. There are various methods such as extrusion, tensile and stress for manufacturing square pipes. Another method on which studies have focused in recent years is the re-forming of round pipes in order to turn them into ...
متن کامل