title: Dynamics of drag and force distributions for projectile impact in a granular medium.
abstract: Our experiments and molecular dynamics simulations on a projectile penetrating a two-dimensional granular medium reveal that the mean deceleration of the projectile is constant and proportional to the impact velocity. Thus, the time taken for a projectile to decelerate to a stop is independent of its impact velocity. The simulations show that the probability distribution function of forces on grains is time independent during a projectile's deceleration in the medium. At all times the force distribution function decreases exponentially for large forces.
authors.affiliation: Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA. picacia@na.infn.it
authors.forename: Massimo
authors.initials: M
authors.lastname: Pica Ciamarra
authors.forename: Antonio H
authors.initials: AH
authors.lastname: Lara
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Lee
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Goldman
authors.forename: Inna
authors.initials: I
authors.lastname: Vishik
authors.forename: Harry L
authors.initials: HL
authors.lastname: Swinney