Art Eatman
Moderator In Memoriam
I allus heard about infinity/monkeys/typewriters/Shakespeare's works. Fer some reason I wuz reminded...
, Art
, Art
MythBusters: Bullets Fired Straight Up
- Thread starter MikeJackmin
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trapperjohn
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- Apr 14, 2004
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- 567
tell you what taurus, go get 1 lb mass of chicken feathers, and 1 lb mass of lead and then measure the weight of both and get back with us.
I assure you the weight will be the same.
if the wieghts are are different you can rewrite all the physics books.
I assure you the weight will be the same.
if the wieghts are are different you can rewrite all the physics books.
Taurus 66
Member
#1. Since it's Christmas, I'll bet you the house 1 lb mass of chicken feathers, a 1 lb mass of lead, don't weigh the same as Sunday mass.
#2. Where the heck am I going to get chicken feathers at this hour?? The back room of a Popeyes restaurant?
#3. I could rewrite all physics books if ... ? Why? The current confusion is enough entertainment.
Upsidey sidey down and a initty initty out!
Up is down and left is right, fast is slow and black is white,
Red is blue and big is small, winter's summer, spring is fall,
Top is bottom, crooked's straight, the number one is really eight,
Hard is soft like sweet is sour, a century is just one hour.
MERRY CHRISTMAS EVERYONE!!! NOT HAPPY HOLIDAYS!!!
I hope you all get what you've been wanting, especially all you bright scientists.
EZ CZ75
Member
I just had to put in one more word that I find it funny how much time we all just put into a moot point on the internet.
Isn't techonology grand!
Isn't techonology grand!
SkyDaver
Member
Herself said:
Sigh. Remember air resistance? Two ping pong balls, one unaltered, one filled with glue. They will have exactly the same drag coefficient, but because one is heavier, its terminal velocity will be greater because we are not on the moon! It's certainly possible that the height of out stretched arms may not be enough for a standard ping pong ball to reach terminal velocity, in which case both balls might hit nearly at the same time, but I think that it will be a perceptible difference (might have to try it out this weekend)
If it is not, then dropping those two objects from a second story window almost certainly will show a difference.
Of course, I only have about seven hours of freefall, so what do I know about air resistance.
Herself said:
One thing to remember is that he was talking about a .50BMG, which is most definitly supersonic.
found a calculator at http://exploration.grc.nasa.gov/education/rocket/termvr.html
Plugging in the numbers, it gives a terminal velocity of a 750 grain .50BMG at 215.5 feet/second. Assuming a drag coefficient of .2(quite a streamlined bullet).
Speed of sound is 1,116 feet/second. So, yes, the bullet will start slowing the moment it leaves the barrel, despite being pointed straight down.
I'm sure that 215.5 ft/s is enough to kill, especially given the huge bullet size.
Uhh, isn't the formula for mass:
Mass=weight/acceleration of gravity??
conversely:
Weight=mass times acceleration of gravity
No allowance for wind resistance there, and no change for size of object.
Mass of 1 lb object is same no matter what the material or where it is moving, IMO.
It would take the same force to stop or deflect a lb of feathers or a lb of lead while in motion.
Obviously wind resistance exerts a greater force on a large body than on a small body, thus the small body will fall faster in air.
In a vacuum, it doesn't matter, the acceleration of gravity is the same on all bodies, and all will fall at the same speed. Some will hit the ground with greater force if the mass is greater.
Mass=weight/acceleration of gravity??
conversely:
Weight=mass times acceleration of gravity
No allowance for wind resistance there, and no change for size of object.
Mass of 1 lb object is same no matter what the material or where it is moving, IMO.
It would take the same force to stop or deflect a lb of feathers or a lb of lead while in motion.
Obviously wind resistance exerts a greater force on a large body than on a small body, thus the small body will fall faster in air.
In a vacuum, it doesn't matter, the acceleration of gravity is the same on all bodies, and all will fall at the same speed. Some will hit the ground with greater force if the mass is greater.
SkyDiver did not say "tennis balls"-- he said "table tennis balls." Most folk call these "ping pong balls." Unweighted ping pong balls will reach terminal velocity from shoulder height. They will NOT reach TV from shoulder height if filled with water-- they will continue to accelerate all the way into the ground.
According to the NRA Firearms Fact Book (published 1964) the army did testing on bullets in free fall and determined the drag factor of the bullet (BC) is the factor that determins the speed of a falling bullet. The only force acting on a bullet fired straight up @ 90 degree is gravity. It will gain speed until drag force equals the pull of gravity, at which point the bullet will stop gaining velocity. They calculate a 30-06 fireing a 180 gr PSP bullet will reach a altitude of 10120 ft. The max velocity of the bullet in fall will then depend on its attitude as it drops. A bullet can fall base first, turn over and fall point first, or tumble. They calculated the terminal velocity would be 180 fps for one tumbling, 323fps base first and 457 fps for a bullet fallng point first
Fine, SkyDaver, but you're quibbling. You wrote:SkyDaver said:
"You can prove that weight matters yourself. Go buy some table tennis balls. Make a small hole in one, and fill it with liquid (Elmer's glue might be good, since it would set after a bit.)
"Drop both of them from outstretched arms. The filled one will hit the ground first."
You didn't write "drag." You wrote "weight." Perhaps you wrote in haste?
With respect to the acceleration due to gravity of a dropped object, weight does not matter.
I have none, unless one counts the few seconds at a time doing silly things with a light airplane. It is possible to understand the physics underlying a thing without experienceing it, just as it is possible to experience a thing without understanding it.
But it looks like you and I are on the same page in the end.
--Herself
That means that the round trip will be about 4 miles (2 up and 2 down). My back of the envelope WAG says that the time of travel will be around 40 seconds. Remember, it's moving quite slowly on the way down. Anybody got the wind drift numbers for a 30-06 bullet during a 40 second flight? EVEN if the bullet is fired EXACTLY straight up, a light wind will move that bullet a LONG way while it makes a 4 mile round trip.
Handgun bullets won't go that high, but we're still talking about a round trip that far exceeds a mile and time of travel that gets up around half a minute. Wind drift is going to be tremendous. Clearly the fact that a bullet lands a long way from where it is shot is NOT sufficient evidence to prove that it wasn't shot straight up.
VARifleman
Member
F=ma. force=W when a=acceleration due to gravity. They will weigh the same when in the same area. Note that I said that their weight will be the same, not that there weight = their mass. Units here... F (N)= m(kg) * a(m/s^2)Taurus 66 said:
F[g]=Wmg? What in the heck do you think this is? Well...I'll let you know...it's just a jumble of letters put together by someone who is ignorant in physics. Afterall, I stated earlier that F[g]= W.
:banghead:
Time to go back to school for some of ya'll...
VARifleman
Member
Get the amount of something with low density (like feathers) that equals 1 kg of mass, and then get its weight (in Newtons). The weight will be 9.8 N. Now get 1 kg of lead, steel, or some other metal. Weigh it as last time, it will be 9.8 N as well (As long as YOU didn't screw up any of the measurements).Taurus 66 said:#1. Since it's Christmas, I'll bet you the house 1 lb mass of chicken feathers, a 1 lb mass of lead, don't weigh the same as Sunday mass.
#2. Where the heck am I going to get chicken feathers at this hour?? The back room of a Popeyes restaurant?
#3. I could rewrite all physics books if ... ? Why? The current confusion is enough entertainment.
Upsidey sidey down and a initty initty out!
Up is down and left is right, fast is slow and black is white,
Red is blue and big is small, winter's summer, spring is fall,
Top is bottom, crooked's straight, the number one is really eight,
Hard is soft like sweet is sour, a century is just one hour.
MERRY CHRISTMAS EVERYONE!!! NOT HAPPY HOLIDAYS!!!
I hope you all get what you've been wanting, especially all you bright scientists.
VARifleman
Member
It means exactly what we've been telling you. Mass is independant of gravity whereas weight is dependant on it. Two objects of the same mass in the same location will have the same weight. In the metric system, mass measured in kg, weight in Newtons will be 9.8 times greater than mass. That's because F=ma where a=g=9.8 m/s^2 For the english system, the pound is a weight, whereas the slug is a mass. The weight in lbs will be 32.17 times higher in value than its mass in slugs for the same reason, F=ma where a=g=32.17 ft/s^2.Taurus 66 said:The mass of an object is different from its weight. Hmmm ... What do you suppose this means?
Stick to trapping buddy
I'd suggest against arguing physics with either of us. You won't win.
I have seen a lot of gunnish discussion boards address a lot of mathematical notions, but there's nothing so entertaining as watching these things go down on THR. Times like this, it seems like the entire membership of this forum is made up of engineers.
Delightful.
On a side note, I'm from Erie, PA, and a little girl caught a falling handgun round in the head a few New Years ago. She was wounded, but survived. If I had fired a round into the air that night, I'd fell absolutely rotten thinking that it might have been mine that hit her. One more reason not to shoot guns into the sky.
Delightful.
On a side note, I'm from Erie, PA, and a little girl caught a falling handgun round in the head a few New Years ago. She was wounded, but survived. If I had fired a round into the air that night, I'd fell absolutely rotten thinking that it might have been mine that hit her. One more reason not to shoot guns into the sky.
trapperjohn
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- Apr 14, 2004
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- 567
mass and weight can actually be a difficult concept for people to get their heads around when it is first contemplated.
mass is defined as an objects resistance to change in motion, or its resisitance to accelerating. a clear cut definition of mass was not really needed untill newton came up with the relationship F=ma showing that a more massive object is harder to accelerate. people are a little more used to thinking in terms of weight because we judge the "massiveness" of an object either by lifting it and noting the difficulty in overcoming the gravitational pull on it, or by using a scale such as a bathroom scale that really just measures force. sometimes people test their grip by squeezing a bathroom scale to see what kind of force they can generate, this shows that what is really being measured is a force, and a weight is a force.
one means of measuring mass is probably the oldest method of measuring weights called the balance scale. A beam is supported in the center and each end has a tray suspended from it. The object to be "weighed in the balance" is placed in one tray, known "weights" (which are realy masses) are placed in the other tray untill the beam is horizontal. Since the force of gravity is the same on each mass gravitational effects are cancelled out and the mass can be determined. This is a good illustration to show that it doesnt matter wither you are using lead or chicken feathers or lead or reindeer antlers. if one will recall the known masses used in these cases is usually lead or brass. someone measuring the weight, or mass of feathers would not demand that the known weights used to measure it also be feathers, they would be content to use any known weight regardless of its composition.
This attribute called mass is dependant only on the object and independant of its surroundings, including any forces acting on it such as gravity. Weight, on the other hand is the force exerted by a mass due to gravitational pull.
it can be noted that if 1 lb force is applied to 1 lb mass the acceleration can be measured to be 32.17 ft/s^2. the unit of mass that 1lb force will cause to accelearate at 1 ft/s^2 is called the "slug" numerically it is equivelant to 32.17 lb mass. a pound mass is defined as the amount of mass that will exert 1 lb force due to gravity at sea level. SI units are significantly eaiser to deal with where a 1 newton force will cause 1 kg mass to accelerate at 1 m/s^2.
mass is defined as an objects resistance to change in motion, or its resisitance to accelerating. a clear cut definition of mass was not really needed untill newton came up with the relationship F=ma showing that a more massive object is harder to accelerate. people are a little more used to thinking in terms of weight because we judge the "massiveness" of an object either by lifting it and noting the difficulty in overcoming the gravitational pull on it, or by using a scale such as a bathroom scale that really just measures force. sometimes people test their grip by squeezing a bathroom scale to see what kind of force they can generate, this shows that what is really being measured is a force, and a weight is a force.
one means of measuring mass is probably the oldest method of measuring weights called the balance scale. A beam is supported in the center and each end has a tray suspended from it. The object to be "weighed in the balance" is placed in one tray, known "weights" (which are realy masses) are placed in the other tray untill the beam is horizontal. Since the force of gravity is the same on each mass gravitational effects are cancelled out and the mass can be determined. This is a good illustration to show that it doesnt matter wither you are using lead or chicken feathers or lead or reindeer antlers. if one will recall the known masses used in these cases is usually lead or brass. someone measuring the weight, or mass of feathers would not demand that the known weights used to measure it also be feathers, they would be content to use any known weight regardless of its composition.
This attribute called mass is dependant only on the object and independant of its surroundings, including any forces acting on it such as gravity. Weight, on the other hand is the force exerted by a mass due to gravitational pull.
it can be noted that if 1 lb force is applied to 1 lb mass the acceleration can be measured to be 32.17 ft/s^2. the unit of mass that 1lb force will cause to accelearate at 1 ft/s^2 is called the "slug" numerically it is equivelant to 32.17 lb mass. a pound mass is defined as the amount of mass that will exert 1 lb force due to gravity at sea level. SI units are significantly eaiser to deal with where a 1 newton force will cause 1 kg mass to accelerate at 1 m/s^2.
Taurus 66
Member
VARifleman said:
It's not about winning for me. It's only about killing time. It's about victory for all you wonderful scientists here, but I bet you're more than just a trapper. You probably deliver firewood too. I need a face cord, or don't you protract that kinda mass along the curve? It's gonna get cold again after the big day tomorrow.
PEACE
trapperjohn
Member
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- Apr 14, 2004
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you wer quoting someone other than me.
you are correct, Trapperjohn is a nickname i picked up a long time ago when I actually did run a trapline. Unfortunately I havent done any in over 15 years.
my current occupation is as an engineering professor. Therefore I spend my days trying to pound sound principles into engineering students such as VAririfleman, and i used to teach physics as well to students that were not on an engineering tract. As an educator in real life my goal is not to win or lose, it is to educate.
Taurus 66
Member
trapperjohn said:
What's the difference?! 5 in one, a half Canadian dozen in the other ...
trapperjohn
Member
- Joined
- Apr 14, 2004
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- 567
whats the difference? about the same as there is between mass and weight
JMO, but it OUGHT to be about informing, or exchanging information and learning. There's plenty of static on the web, and there are plenty of threads that are purely social. Why "kill time" cluttering up a thread that has a good chance of being a good source of information?
VARifleman
Member
Well, I'm the one you quoted, and I'm not a trapper (not trapperjohn afterall, I'm VARifleman). I'm a civil engineering student at NC State, as for "delivering firewood", that's not what I do. I am currently working for a boiler repair company near my hometown in Northern VA. You really don't make much sense at all in this thread, Taurus.Taurus 66 said:It's not about winning for me. It's only about killing time. It's about victory for all you wonderful scientists here, but I bet you're more than just a trapper. You probably deliver firewood too. I need a face cord, or don't you protract that kinda mass along the curve? It's gonna get cold again after the big day tomorrow.
PEACE
Taurus 66
Member
VARifleman said:
WHAT'S DA DIFEERREEENNNNCCCCE?! Like there's some difference between a dime minted in Denver or in DC! Give me a break!!! I can toss a dozen of you geeks to the wind and get blown back at me 12 calculators, 11 slide rulers, 10 protractors, 9 sharpened pencils, 8 floppy disks, 7 paper cuts, 6 thick frame glasses, FIVE GOLDEN RULES, 4 physics books, 3 paper clips, 2 bogus degrees and a cartridge in a pear tree!
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