What happens to bullets fired upwards into the air?

Question

Quite often (on the news for example) you see people in crowds who fire their guns into the air in celebration. Presuming the guns they fire are loaded with bullets and not blanks, do the bullets that fall back to the earth ever injure or kill people, or is their decent slowed enough by gravity not to do harm?

Answer 1

Gravity only "slows" the bullet during 1/2 of its total trip, during the other half, gravity accelerates the bullet.

As the bullet rises into the air its velocity is continually decreasing as the force of its own weight (force due to gravity) as well as the force of air resistance, act to accelerate it downward. At some point the bullet will come to a stop and then begin falling. Afterward, gravity acts to increase the bullet's speed while the air resistance works in the opposite direction. The magnitude of the force of air resistance depends on the speed of the bullet (the faster it does, the harder the air pushes back on it). Eventually, the bullet will reach what is known as the "terminal velocity", where the force of gravity equals the force of air resistance, and the bullet stops accelerating (net force = 0).
The terminal velocity for an object depends on several factors including the object's mass and shape, as well as the density of the fluid it is moving through. The terminal velocity for a bullet is lower than the speed at which it comes out of the gun in most cases, so the bullet will never be traveling as fast as it was while leaving the barrel when it hits the ground...but still, I would still not want it to hit me.

Answer 2

First, the problem with bullets IS gravity. They will slow as they travel upward until they momentarily stop, and then, gravity will cause them to accelerate back downward.

There are two factors affecting the speed of a bullet. The first is gravity, and the second is friction with the air.

Any falling object in an atmosphere will have what is called terminal velocity. This is the fastest that an object can fall, and is the point where acceleration due to gravity is balanced with the slowing of the object due to friction.

If the falling of the object is due to pure gravity, there is a possibility of injury simply by being struck with an object that is falling at it's terminal velocity. Expirements have shown though, that such injuries from bullets are unlikely to be life-threatening if the bullet is simply falling or tumbling as would be the case after reaching it's apex, stopping and then falling.

Much more dangerous is when the bullet is not fired straight up. In this case, the bullet maintains it's spin and trajectory, and a great deal of momentum. These are quite capable of seriously injuring and killing an individual.

In the end, it's never safe to discharge a weapon in or around a crowd. One should always have a clear target, be aware of what's in front and behind that target, and not fire until that target is clear. As many rifles can effectively fire a round a mile or more, they aren't toys to be played with lightly.

Answer 3

The bullet slows by gravity as it travels upward. At the apex (highest point) of it's trajectory it reaches zero velocity and begins to fall back to the earth. Disregarding friction the bullet would hit at the same velocity as it left the gun barrel, making it a deadly object. HOWEVER in earth atmosphere the bullet would (because rifling of the barrel is irrelevant) tumble as it fell. I would rough estimate the falling velocity to be somewhere around the same as a human being... about 120 mph. While this would significantly hurt if it hit you, the odds of this being a lethal impact are between the realms of extremely slim and none.

The danger occurs when someone is not pointing their weapon upwards, but rather at an angle. Because gravity only works in the up down direction, the bullet does not significantly slow in the horizontal direction. If the angle is shallow enough, the bullet will still be travelling at lethal speed when it strikes. With this case, however, the chances of hitting someone are very small.

Answer 4

They fall back to earth eventually. Bullets from typical handguns and assault rifles are not really very heavy (usually between about 5 and 15 grams), so they reach terminal velocity fairly quickly on the way back down. The terminal velocity of many bullets does actually put enough force on the projectile to penetrate the skin, so it is possible that they would hurt someone (though probably not kill them)... if that someone were standing in the wrong place.

You can certainly find accounts of people who are injured by "falling" bullets, but it's relatively few compared to the number of bullets used in incidents like you describe.

Answer 5

Yes, the bullets ALWAYS fall back, and sometimes they injure or kill people. That's why shooting into the air is unlawful. Air resistance will slow them a little, but not enough to matter. Gravity slows the ASCENT of the bullet, then accelerates its DESCENT. If air resistance were not a factor, the bullet would hit the ground at the same speed at which it was fired. Remember parabolas in Alg 1?

Answer 6

Bullets fired in the air can injure or kill someone. The bullet will continue to go up until gravity reduces its velocity enough to stop and come back down. On its way down it regains velocity and it has enough speed when it hits the ground that if it hits someone they could die, but usually the bullet doesn't land anywhere near where it was fired from.

Answer 7

each and all the gun powder interior to bullet is burned out and the empty cap falls decrease back to the floor ... it falls with plenty lesser velocity than what it went up whilst fired. And approximately dropping a bullet from a skyscraper will harm a man or woman in a matching way which a matching shape and mass substance will harm yet won't kill absolutely everyone for specific.

Answer 8

if we do not consider air resistance, the force applied to the bullet as it fires upward will be the same force it will apply to the target when it goes down... it will follow a parabolic trajectory which means that people who get hit by stray bullets experience the same as people who get hit directly... although there is air resistance, the shape of the bullet allows it to become aerodynamic and therefore air resistance has very little effect on it... that's why firing a loaded gun up in the air is usually illegal because oftentimes people (less than 50% of bullets fired in the air hit innocent people) get hit by these stray bullets...

Answer 9

This happened to my family once on 4th of July. Someone was firing a gun and the bullet went through our roof and landed in the laundry room. The police took the bullet with them. And he said the bullet's velocity doesn't change when it comes down so yes it could kill someone.

Answer 10

It could kill because when the bullet goes down, it possesses the same force at the same point where the fun is fired upward.

To make it easier to understand, as the bullet goes up, it starts to slow down its ascent until it reaches its maximum height. However, as the bullet descends, it gathers force until it reaches the same force when it reaches the height (or point) where the gun was fired. Thus, somebody who would be hit by a bullet fired upward would suffer the same injury as if he was shoot directly.