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Now playing: Journey - Don't Stop Believin'
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"I go to Indianapolis every year, to see the the Indy 500. I go there with friends to drive and race. Every year when they go there to qualify, they usually have to go as fast as they possibly can to get a front row position. They put nitro in their cars sometimes instead of the fuel that's intended to be in the cars, so that the cars will go faster. And they do, for 5 or 10 laps... then they blow all to Hell." - Evel Knievel




When a solid projectile strikes a granular layer, the impact forms a crater. This impact cratering phenomenon is basically simple. It can be described as a one dimensional motion, and the underlying physics is only classical mechanics. Nonetheless, a lot of dissipative macro grains, granular media, bring intriguing features to such a simple phenomenon. Surprisingly, nobody exactly knows how a projectile stops in a granular layer, even in terms of phenomenology. Some candidates of the force model have been proposed recently. To clarify which one is the best at describing a wide range granular impacts, we are measuring the velocity of the impact and discussing its dynamics.