Photo courtesy of DuPont Vests made with DuPont(TM) Kevlar® protect law enforcement officers from risks they face on the job.

On police dramas and in action movies, someone can slip on a bulky vest, and suddenly they're practically invincible. While the entertainment industry exaggerates things a little, "bulletproof vests" really do exist. And these forms of soft body armor do stop some bullets.

To understand the basic idea of soft body armor, think of a soccer goal. The back of the goal is a net. The net is formed by many long lengths of tether. The tethers are interlaced with each other and fastened to the goal frame. You kick the soccer ball into the goal. As it hits, the ball pushes back on the tether lines at that particular point. Each tether extends from one side of the frame to the other. This scatters the energy from the point of impact over a wide area.

The energy is even more spread out because the tethers are interlaced. When the ball pushes on a horizontal (side to side) length of tether, that tether pulls on every interlaced vertical (top to bottom) tether. These tethers in turn pull on all the connected horizontal tethers. In this way, the whole net works to absorb the ball's inertial energy, no matter where the ball hits.

Under a microscope, soft body armor looks very similar. A bullet travels much faster than a soccer ball. So the "net" in soft body armor needs to be made from stronger material. The most famous material used in body armor is DuPont's KEVLAR® fiber. KEVLAR® is lightweight, like a traditional clothing fiber. But it's incredibly strong -- five times stronger than a piece of steel of the same weight.