Bulletproof vests on today's A Moment of Science. Do not, I repeat DO NOT, try this at home.
Whether it be on TV, or in real life, we've all seen the bulletproof vests that cops where when executing important missions. Lets talk a little bit about what makes the body armor so effective.
When feeling a bulletproof vest, you'll find it to be very stiff. Stiff enough, in fact, to stop a bullet. It works kind of like a soccer net. When you kick the ball into the net, it absorbs the energy of the ball and eventually stops its forward motion. The net inside a vest is a dense, layered weave that includes a synthetic material called Kevlar, which is lightweight, but incredibly strong.
A tightly woven Kevlar net can absorb a huge amount of energy. Plus, the net is coated by a stiffening resin and sandwiched between two layers of sturdy plastic. When a bullet hits, the web "gives" in order to distribute the bullet's energy over the entire surface of the vest. The material is so strong that the web doesn't have to give very much in order to stop the bullet.