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PhanthomJay
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Aug12-08, 08:26 AM
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Quote Quote by 1337 View Post
1. The problem statement, all variables and given/known data

Part 1:
We have all seen news footage from the Middle East in particular, where heavily armed gunmen toting AK-47 assault rifles fire their weapons into the air. What happens to the bullet after the trigger is squeezed?
Unless it hits a duck, what goes up, must come down, somewhere.
Can it be dangerous for people nearby when the bullet comes back down?
Yes, it could be. In a rare case, it could cause death. The terminal velocity of a bullet can, unlike the low terminal velocity of a falling coin, be surprisingly rather high.

Part 2:
Assume the bullet is gyroscopically stable. Would wearing a modern army Kevlar helmet protect you?
Yes. Just don't look up.


I have found out that the muzzle velocity on an AK-47 is around 710m/s and a Modern Kevlar Helmet can handle up to 610m/s.
Due to air resistance, the speed of the bullet upon return must be less than 710m/s, a lot less. That helmet should, I would think, easily handle it, if your data is correct.