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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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Despite the friction forces early appearance in the first weeks of introductory physics and mechanics courses and simple form (Fsliding friction = mkN, Fstatic friction ≤msN, where N is the normal force), it is a strongly non-linear force that produces both subtle and surprising dynamical effects. This talk will present an overview of our experimental and theoretical work exploring the application of friction to the transport and manipulation of objects in contact with and sliding on a periodically oscillated surface. The key to achieving frictional transport (as well as locomotion in self-propelled objects) utilizing periodic forcing is breaking the temporal symmetry of the contact forces. In the context of our work, I will discuss how modulation of N can be used to drive the motion of localized and extended objects.
The resulting object motion can be described in terms of velocity fields for which the mean (cycle averaged) velocity of an object is determined by its position. By varying the vibration, velocity fields with non-zero spatial divergence can be generated that allow the simultaneous and open-loop collection, dispersion, and transport of multiple objects simultaneously. In certain cases, fields and field sequences can simultaneously move multiple objects between arbitrary positions and, potentially, along arbitrary trajectories as well. Our understanding of frictional transport is by no means complete, and there remain important open questions concerning the existence and generation of prescribed velocity fields.
