Soil hardens when struck harder
SOIL AND sand actually get stronger when they are struck harder. Duke University researchers in the US developed techniques that enabled them to simulate high-speed impacts in artificial soil and sand in the lab. The findings help explain why attempts to make ground-penetrating missiles go deeper by shooting them harder and faster have had limited success. Projectiles experience more resistance and stop sooner as their strike speed increases, shows the research which may lead to better control of earth-penetrating missiles designed to destroy enemy bunkers.