So what if your bullet does go through a wall?

JohnKSa said:
Therefore a bullet would fall faster than a hailstone of the same size.
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<nitpick>It would fall harder, not necessarily faster. Acceleration by gravity is about 9.8 m/s/s no matter how much or how little you weigh, up until you get near terminal velocity. F=MA; the greater force is due to the greater weight.</nitpick>

Sorry, my last girlfriend was a physics major and I picked up some of her habits. I suspect you knew all of this, given the rest of your post, but it's a stiff reflex.
 
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It would fall harder, not necessarily faster. Acceleration by gravity is about 9.8 m/s/s no matter how much or how little you weigh, up until you get near terminal velocity.
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More nitpicking (from a Mechanical engineer this time:D). Thing only fall at 9.81 m/s/s in the absence of drag. In all real life scenarios drag is present which means that the object with the higher sectional density (which most shooting enthusiasts know to be ratio of mass to cross sectional area) will not only accelerate faster, but reach a higher terminal velocity as well.

Note: Once you start talking about objects that tumble in flight the situation gets even more complicated as the relevant cross section is constantly changing.
 
It would fall harder, not necessarily faster. Acceleration by gravity is about 9.8 m/s/s no matter how much or how little you weigh, up until you get near terminal velocity.
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Axion is correct, this is only true in the absence of drag (air resistance). This is a common misconception due to the fact that people remember basic physics problems but forget the assumptions and conditions specified in them. Your statement would be correct for falling objects in a vacuum but once you incorporate air resistance everything changes.

Here's a decent treatment of the topic from a source that most would consider unimpeachable.

http://www.grc.nasa.gov/WWW/K-12/airplane/falling.html
 
Keep in mind that most guns "fired in the air" are not fired at 90 degrees to the ground, but at some angle, which means the bullet is traveling in a parabolic arc.

And depending on distance, coming down from that arc can indeed still be a bullet at lethal velocities, especially a pointed, more aerodynamic rifle bullet.
 
Keep in mind that most guns "fired in the air" are not fired at 90 degrees to the ground, but at some angle, which means the bullet is traveling in a parabolic arc.
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Correct. A bullet traveling in an arc will have more velocity than a bullet that is simply falling--vector sums and all that...
 
JohnKSa said:
Axion is correct, this is only true in the absence of drag (air resistance). This is a common misconception due to the fact that people remember basic physics problems but forget the assumptions and conditions specified in them.
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I don't think I forgot the assumptions, but isn't drag relatively negligible (relative to mass between a bullet and similarly-sized/reasonably spherical hailstone), up until you start getting near the hailstone's terminal velocity? I don't remember the details very well, but I think it's quite small next to the mass difference.

Once your hailstone hits terminal velocity, the bullet goes quite a bit faster, of course, but I'm not sure if the bullet gets there, starting from the ground and all.

It's too early to be doing physics problems. -.-
 
...isn't drag relatively negligible...
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Air resistance is pretty significant. It's often neglected in problems given to students--not because it's negligible but because it can be quite difficult to calculate.

The more aerodynamic object will accelerate faster (since there's less force from air resistance fighting that acceleration) and will eventually reach a higher velocity before the air resistance balances the force of gravity.
I'm not sure if the bullet gets there, starting from the ground and all.
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A bullet will travel upwards thousands of yards--experiments have shown a 30-06 rifle bullet will reach a height of around 9000 yards. That's enough time for the bullet to attain terminal velocity on the way down.

Interestingly enough, the person (Julian Hatcher) who did the experiment calculated that the bullet would have attained a height of over 21 MILES had there been no air resistance. Drag can not be neglected.
 
Oh... right. That comment about "9000 yards" reminded me: bullets go really fast and the faster you go, the more drag matters.

I remember doing some simple drag problems and getting reasonably small answers (ideal non-tumbling cylinders and spheres, dropped from rest on a decent-height building), but... bullets go a lot faster than that. That's why they're useful.

Sorry for the hijack, everyone; I'm an idiot.
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Had a 9mm go off in my house, went through the carpet and foam padding, through the 2x10 hand cut floor and out of my basement wall that was concrete block, I wouldn't have wanted to be on the outside waiting for it!!! You would think it woundn't have made it through the floor. As for going through a wall, you know it's going to go through...
 
These will definitely have enough "oomph" to be lethal and it's not that hard to find evidence to support that fact. I did an internet search looking for deaths from descending bullets some time ago and found enough documented instances to convince even the most skeptical.
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Here's a first hand anecdotal example: I covered the first Gulf War as a photojournalist, with the 1st Marine Div, and ended up in Kuwait City the day it was liberated (SEALs and maybe CIA paras were there the day before, at least). The city was going totally wild with celebration for days, mainly along the seaside boulevard near the US Embassy. There were the usual wingnuts capping off their AKs into the air like firecrackers...hundreds of rounds. Here's the "joke": instead of aiming out over the sea just across the road, they were usually pointing their muzzles over the city. You guessed it...every day, people killed and wounded by falling projectiles. Pure genius!

On New Years, many LAPD patrol units working the late show pull into parking garages at midnight, because of falling lead.
 
A bit off subject but locally in a 3 story apartment complex where the 1st level offered attached garages. Several years back, Man decides to commit suicide by carbon monoxide poisioning in a closed garage. He was successful but also killed the guy asleep in the 2nd floor apartment above the garage.

Actions have consequences.
 
all physics aside, i seem to remember massad ayoob writing about shooting at a downward angle to avoid doing something stupid when you're not sure of your backstop. i'd rather risk my life dodging some bg with a limp than risk shooting the little girl down the street. no matter how brave a bg might be, i'd think a weapon pointed at his family jewels would be more than enough deterrent.
 
I understand the bullet from the sky will fall at 9.8 meters per second max.

thats like being hit with a bullet coming at you appx 30 FPS

a reguarl bullet hitting you can be 1000 FPS.

how is a bullet falling straight from the sky kill you ? at 30 FPS ?
 
all physics aside, i seem to remember massad ayoob writing about shooting at a downward angle to avoid doing something stupid when you're not sure of your backstop. i'd rather risk my life dodging some bg with a limp than risk shooting the little girl down the street. no matter how brave a bg might be, i'd think a weapon pointed at his family jewels would be more than enough deterrent.
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I think if your bullet makes it through the BG, you wont have to worry about the wall behind him and the little girl behind that...
 
I think if your bullet makes it through the BG, you wont have to worry about the wall behind him and the little girl behind that...
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yeah well if you have two BGs without body armor lined up one behind the other ill bet my 357 mag i can bag both of them with one shot from the same.

i think you should always be worried about whats behind the target
 
inaccuracies

OK, There is some good info here, but also some inaccuracies.

1) ACCELERATION due to gravity is 9.8 m/s². That's an approximate value, it decreases as an object's distance from the center of the earth increases. There is a difference between speed and accelleration, and they are related by the formula v=at (velocity = accelleration x time) . That means that it is travelling at 9.8m/s after one second, 19.6 m/s after 2 seconds, 29.4 m/s after 3 seconds, etc. Even if the accelleration is constant, the velocity would change.

2)In the case of the bullet fired into the air, the accelleration isn't constant. The net vector accelleration is the sum of the alleration due to gravity (which changes slightly as elevation increases) and negative accelleration (decelleration) due to wind resistance (which is a function of the projectile's speed, ballistic coefficient, flight profile, and air desity)
 
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they are related by the formula v=1/2at (velocity = 1/2 accelleration x time)
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No, it's v = at. So, in the absence of drag, a dropped object is traveling approximately 9.8 m/sec after one second, 19.6 m/sec after two seconds, and so on.

You're thinking of d = (1/2)at^2, which describes distance traveled.
 
I really hope it does not injure anyone. That said, I will only draw and shoot if I preceive a serious, or lethal threat immenanent against me. That trumps any 'maybe', 'possible', or 'might happen' scenarios. It is real, immediate and of a serious/lethal level to me.
 
Obviously it does matter. Who's on the other side of the wall? What about the welfare of people who reside in townhomes, condominiums and work in next door office/business suites?
 
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