Question

If a bullet is fired vertically upwards with a uniform velocityof 250m /s what will be its velocity when it reaches the earth

Answer 1

It would come down at a slower velocity than it went up, but whether it would be lethal or not depends mostly on other factors. I am assuming that by “up at the sky” you mean straight vertically. (Actually an important point since it determines whether it tumbles back down, or spirals back down. But we won’t over complicate things here.)

Our standard force is gravity. Every object has a “terminal velocity” in our atmosphere. Because of air resistance, if you drop an object it will eventually reach a maximum velocity and not go any faster. Think of dropping a ping pong ball and a bullet at the same time. The ping pong ball would reach it’s terminal velocity fairly quickly and then just continue down at that speed. But the bullet too would eventually reach its terminal velocity, although it would take longer and would be going much faster. But it would eventually max out at a certain speed and not go any faster.

When you fire a bullet, the explosion of the cartridge forces the bullet out at a much higher speed than its terminal velocity. A typical rifle bullet is traveling around Mach 3 when you fire it, a handgun bullet about Mach 1 (700 miles per hour roughly) plus or minus a bit. I can’t tell you what the terminal velocity of a dropped bullet is since it depends on the bullet, but I’m sure it’s not breaking the sound barrier.

So you fire your handgun up, the bullet reaches its maximum height, stops, and starts to drop back and eventually gets to its terminal speed. Let’s just say it’s 100–200 miles an hour.

Chances are it won’t hit anyone. If it does, a very small probability, it would most likely hit a part of their body that would not cause death. Also remember that about 70% of the time, people who are shot from a gun do not die from their bullet wound even though that bullet is going Mach 1 or faster.But it could hit a part of their head in such a way that it does cause death. What if a person was looking up and it punctured their eye, or went into their mouth and throat and choked them? Or what if it were a baby with a “soft spot” on the top of his/her head? Or somebody who had a thin or sensitive skull for some reason? Very low chance of any of these, but it could happen. And, it does happen. It happened within the last 12 months to an innocent young girl playing in her yard with her father.