# Firing Bullets Upwards

1. Aug 12, 2008

### 1337

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? Can it be dangerous for people nearby when the bullet comes back down?

Part 2:
Assume the bullet is gyroscopically stable. Would wearing a modern army Kevlar helmet protect you?

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.

2. Aug 12, 2008

### PhanthomJay

Unless it hits a duck, what goes up, must come down, somewhere.
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.

Yes. Just don't look up.

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.

3. Aug 12, 2008

### stewartcs

If the bullet keeps its trajectory it could be just as lethal. If it does not, then it will be limited to its terminal velocity and probably not lethal.

CS

4. Aug 12, 2008

### Alfi

Funny to suggest this here, but...

Check out Myth Busters. They had a show on this very myth.