Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear Force Propagation during Granular Impact   We experimentally study nonlinear force propagation into granular material
during impact from an intruder, and we explain our observations in terms of the
nonlinear grain-scale force relation. Using high-speed video and photoelastic
particles, we determine the speed and spatial structure of the force response
just after impact. We show that these quantities depend on a dimensionless
parameter, $M'=t_c v_0/d$, where $v_0$ is the intruder speed at impact, $d$ is
the particle diameter, and $t_c$ is the collision time for a pair of grains
impacting at relative speed $v_0$. The experiments access a large range of $M'$
by using particles of three different materials. When $M' \ll 1$, force
propagation is chain-like with a speed, $v_f$, satisfying $v_f \propto d/t_c$.
For larger $M'$, the force response becomes spatially dense and the force
propagation speed departs from $v_f\propto d/t_c$, corresponding to collective
stiffening of a strongly compressed packing of grains.

3
The categories of this paper are: physics
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys