Why can’t a bullet proof vest protect you from a knife stab?

Question

I mean, it’s designed to stop a bullet which delivers much more force than a human being can ever produce during stabbing

In: 784

Answer 1

The constant force applied to a much lower surface area means more parting of the individual fibers. The energy stays applied for a longer time and increases instead of immediately disappearing. Whereas a bullet is blunt and the energy quickly dispersing.