Watch mythbusters bullet myths tonight!

[LaEscopeta]

Carrie is pregnant. My nerd side feels sad, almost betrayed.

Haha, yes, mine too. I googled it and it turns out that she had her baby back in June.

I tuned in late, and was wondering if Kari was pregnant or had just let herself go. In the 3 “knock-your-socks-off” bits she seemed to big, a little smaller, then bigger again. I assume they put the show together in a different order than it was filmed.

And I got my wife to watch (even the firearms parts) because she wanted to figure out if Kari was pregnant or not.

You will now be returned to you regularly scheduled firearms thread….

 

[natman]

As I stated, I knew people would question my explanation for the difference in drop time. That being said, my primary purpose was to say the "myth" that any two objects, regardless of horizontal velocity, when dropped will touch ground at the same time is based on a law of physics contingent upon the presence of a Perfect Vacuum, devoid of atmosphere, aka friction. Therefore it is impossible to prove this using the fired bullet example until a perfect vacuum that could contain such a test exists. Therefore, horizontal velocity, due to atmosphere, does in fact affect the rate of fall and will therefore make it near impossible to accurately "bust the myth". In closing, the LAW of physics being tested, cannot be tested or busted accurately, in this manner, because the state of nature required for the law to be tested does not exist in testable conditions.

What difference does air friction make? Same bullet, same gravity. Sure, air friction has a huge effect on the left to right component of the bullet's path, but the up and down component is the same.

 

[youngda9]

A bullet fired horizontal from a gun will not hit ground at the same time a bullet dropped from the same height will.

A bullet fired from a gun does not continue to pint horizontal to the ground. As it falls, the nose tips downward and the bullet accelerates somewhat towards the ground because the velocity vector is no longer horizontal to the ground. Read Jim Carmichael's book of the gun, it is explained in detail.

Mess around with a ballistics calculator program and it can be understood. http://www.handloads.com/calc/

 

[HGUNHNTR]

Can someone explain this new variable gravity thing, Im confused

 

[LaEscopeta]

What difference does air friction make? Same bullet, same gravity. Sure, air friction has a huge effect on the left to right component of the bullet's path, but the up and down component is the same.

The fast moving bullet fired from the pistol creates turbulent flow as in moves through the air. That is air molecules are pushed out of the way of the bullet sudden enough and fast enough to cause them to move in random paths.

The dropped bullet is moving slowly, and air moves around it with laminar flow. That is the air molecules move is smooth, roughly parallel paths around the bullet, coming together again on the back side of the bullet.

Air resistance is greater for turbulent flow than laminar flow, and this greater air resistance acts in all directions, including the up and down component. That is once the air is disturbed enough to go turbulent, it creates a zone of turbulent air all around the moving bullet, that the bullet has to go through on the way down, at greater resistance. Same bullet, same gravity, but greater air resistance for the fired bullet, so the fired bullet falls down slower.

Having said that, the difference in air resistance would be small over the 3 vertical feet drop height of the bullets in the Myth Buster’s test. Their dropped bullet hit the ground 0.03-something seconds before the fired bullet. Maybe this is the result of different air resistance, maybe it is the in-accuracy of their test procedure/equipment/measurement ability.

 

[LaEscopeta]

Can someone explain this new variable gravity thing, Im confused.

Newton’s answer: Gravity varies with the inverse square of the distance between the centers of mass of the objects experiencing the gravity.

Einstein’s answer: An object falling through a gravitational field experiences variable gravity directly proportional to the difference in the object’s acceleration and the local gravitational constant. An object near the earth’s surface falling and accelerating at 32.2 Ft.sec per second experiences no gravity. An object falling at 16.1 ft/sec per second experiences ½ the gravitational force as an object that is not falling.

http://en.wikipedia.org/wiki/Gravitation

(I know, you knew that already, and this wasn’t the variation being referred to.)

You will now be returned to you regularly scheduled firearm related thread…

 

[eye5600]

They could have saved themselves a lot of trouble by consulting a good ballistics calculation program. It would have told them at the range at which the .45 would hit the ground, for example. The fun of the program is actually testing things full size, which is unusual in this age of computer calculations.

I think the point about the effects of the atmosphere is a good one. If the bullets were to drop very far, it would have a big effect, and the effect at 1000 ft/sec is very different from 0 ft/sec.

 

[CoRoMo]

Is it yet viewable anywhere on the net?

 

[mljdeckard]

eye5600 -I think there is under some circumstances, a SLIGHT difference. Not a big difference.

In the grander scheme, imagine a B-17 firing a .50 cal horizontally, with a bullet being dropped at the same time. In between trying to factor lift from the forward motion, whether the gun is perfectly level or aimed up or down a bit, for all intents and purposes, the fired bullets and the dropped bullets are going to hit the ground pretty much at the same time.

 

[eye5600]

In the grander scheme, imagine a B-17 firing a .50 cal horizontally, with a bullet being dropped at the same time.

When I said a big difference, I meant a big difference between in the atmosphere and in a vacuum, not between the two bullets. A bullet dropped from a great height would get to the ground faster in a vacuum.

I agree with LaEscopeta that the air flow around the two bullets is very different, so it may have a big effect on the way the bullet falls.

 

[ny32182]

A vaccume is only needed if two dissimilar objects are subject to the test. (i.e. dropping a hammer and a feather on the moon). Since the bullets are physically identical, the only differences in air resistance that will affect the test are the orientation as they fall: The fired bullet will always have its nose forward, while the dropped bullet will tumble. This will cause *very* small variations in the vertical wind resistance component, but not enough to be independently measurable under the other constraints of the test: low vertical velocity, ruler-measured starting height, etc.

Also, the bullets are concentric, not shaped like an airplane wing, so there is no lift as they travel horizonally... like someone said, the bullet appears to "rise" relative to the line of sight; it does not actually rise unless the muzzle was pointed up. In the Mythbuster test, they fired the bullet with the muzzle laser measured at perfectly horizontal, so the bullet is at its highest point the instant it leaves the barrel.

I believe they did the best they could with the equipment they had, it was a valid test, and their results bore that out. Their observed variation in ground impact time is probably small enough to be attributed to whatever imperfection existed between the hight of the muzzle and the height of the dropped bullet/imperfections in the floor/imperfections in their exact release timing... overall it was very, very close.

 

[C-grunt]

Some of you guys are no fun. Jesus people its a tv show not a bunch of NASA scientists writing a report. Are there going to be inconsistencies in their findings.... of course. Its a show for entertainment not pure scientific discovery.

 

[Erik M]

If Mythbusters really wanted to satisfy the firearm community they would need to have some "armchair gunfighters" from Thr, AR15, firing line, ect. . . to tell them about how physic's and quantum mechanics really work.

 

[DougDubya]

If Mythbusters really wanted to satisfy the firearm community they would need to have some "armchair gunfighters" from Thr, AR15, firing line, ect. . . to tell them about how physic's and quantum mechanics really work.

LMBFBO!*

(Laughing my big fat butt off)

It's funny because it's true.

 

[UnclePete]

Mythbusters is great. It shows people who are not homicidal maniacs taking a healthy interest in guns, and what other show does that?

 

[dom1104]

I love how people critique misinformation on a tv show, and there is enough emphatically stated drivel re: tracers in this very thread lol.


"NO, I think tracers ignite based on some sort of electromagnetic charge given off by friction of water particulate....."

 

[mm1ut1]

Now if a tracer is fired horizontally...........

 

[Cycler]

Dum question - what's in the bullet they were holding with the electromagnet that made it magnetic? Was it the shape of the jacket?

 

[GonHuntin]

Didn't see it, but it probably had a steel core or copper washed steel jacket.

 

[CleverNickname]

I'm surprised no one else mentioned their second NFA violation, with their electrically powered trigger activator on the 1911 they were using in the test.

 

[LaEscopeta]

I'm surprised no one else mentioned their second NFA violation, with their electrically powered trigger activator on the 1911 they were using in the test.

If the trigger activator has to be reset by hand bteween shots, I don't think it would by in voilation of NFA.

 

[Skillet]

while Mythbusters does get some things wrong with things like that involving guns and ammo sometimes, at least they are a popular TV show that looks at guns and (when in a safe environment of handling guns) portrays fun, unlike NBC who looks at guns and portrays a homocidal maniac with dual AK-47's shooting up everything in sight, and that whoever owns a gun is just like that maniac.

thats a good job in my eyes.

 

[ChaoSS]

I'm surprised no one else mentioned their second NFA violation, with their electrically powered trigger activator on the 1911 they were using in the test.

Likely they have a bunch of lawyers checking with the ATF and local authorities on everything. Many things have an exemption for tv purposes though, and I'm sure they got any licenses they needed for it.

 

[Samilitant]

If the measured difference between the two was .03 seconds, then who cares what hits first? It's close enough to say they hit at the same time. That's my take.

 

[lbmii]

To the bullets can fly crowd. Um if there is any discrepancy in the time between when a horizontal fired verses dropped bullet hits the ground then it is due to the inaccuracies of the experiment.

So the gods of gravity give fired bullets a special pass?