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Old 04-30-2016, 08:19 AM
Sasquatch Sasquatch is offline
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Join Date: May 2011
Posts: 149
bullet proof (resistant) vests

That actually is the way most soft body armor works, especially for handgun bullets which tend to be larger diameter and slower. The bullet will be deformed by the impact, which actually helps spread the force and slow it down. It might just drop away, if it doesn't penetrate at all. If it hits harder, or the jacket tears and makes sharp edges, it might penetrate some of the layers of Kevlar and get stuck in the material.

Higher velocity rifle bullets (which are usually also smaller diameter) need hard plates to stop the bullet, usually fragmenting it; Army body armor plates will stop rifle armor piercing rounds even.

The momentum of a bullet impact is going to be less than the momentum from the recoil of firing it, so from a purely physics standpoint, no. However, people getting shot are not as prepared for it as people shooting. They may be off balance, and there is certainly some mental/physiological reaction to "I've been shot!" So falling down is not that unusual, especially if the person is just standing around. Someone in motion, or doing large movements, tend to keep on their inertial path.

Kevlar is still just a fabric, although tough. Getting poked with a finger and getting poked with a hatpin is pretty different, despite maybe being the same overall force. A sharp knife edge concentrates force on a tiny area, whereas a bullet impact is pretty much a really hard finger poke.