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Spelling NAZI XavierOnassis: Did you get something wrong or what ?


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4 hours ago, PhilipIV said:

The birth control pill does not prevent fertilization.

  MOST birth-control pills prevent the sperm and the egg from uniting.

  After conception, you are killing your baby.

  Fancy names like "morning after pill" and other such fancy names are STILL killing your baby.

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5 minutes ago, bgr39 said:

  MOST birth-control pills prevent the sperm and the egg from uniting.

  After conception, you are killing your baby.

  Fancy names like "morning after pill" and other such fancy names are STILL killing your baby.

Wrong. Birth control doesn't prevent fertilization. It prevents connection g to the uterine wall

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13 hours ago, PhilipIV said:

Wrong. Birth control doesn't prevent fertilization. It prevents connection g to the uterine wall

  It depends on what type of birth-control pill you use.

  Some prevent sperm from reaching the egg and others just allow the egg to just drain away before it gets fertilized.

  IF the egg is fertilized, and you purposely destroy it,  THEN you are killing your baby.

  It is as simple as THAT!

  Use a condom, don't leave anything inside her, there are many forms of birth-control, other than killing the baby.

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On 6/24/2019 at 11:14 AM, XavierOnassis said:

Ronans (unaffiliated Japanese Samuri) did not have them either.

Regardless of your poor spelling, you were just WRONG!

 

Silphium, akin to Rosinweed, is a plant that was used in Roman antiquity as a contraceptive. Demand for its contraceptive use was reported to have led to its extinction in the third or second century BC.

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  • 1 month later...

How to calculate speed of shrapnel based on explosive's speed of detonation?

 

exman I'm trying to calculate the initial speed of shrapnel from a grenade.

 

Using the US's M67 hand grenade as a baseline/reference:

 

Total mass: 400g

 

Explosive's mass: 180g

 

Explosive's detonation speed: 8050 m/s (Composition B)

 

Assuming the fragmentation is 1000 uniform pieces of shrapnel, what would be the initial speed of a single shrapnel piece?

 

What would be the initial speed of a single shrapnel piece? Zero, of course. As the (presumed mostly gas) post-reaction (explosion) matter then leaves the locus of the explosion, it drags the shrapnel with it, exercising a force on it, so that it accelerates, as per N2. – Gert Sep 6 '19 at 20:10 

 

When you say "initial speed" I will assume you mean the maximum speed of a single shrapnel piece.

 

Regarding the three bullet points: The first bullet point, in my opinion, is of no help. This is the mass that simply falls to the ground (the local remnants of the grenade). It probably accounts for some of the energy of the explosion since the pieces will obviously be hot. But I suspect it accounts for very little.

 

If the second bullet point gives us the total mass of the 1000 shrapnel pieces, it gives us one of the needed parameters to answer your question. The initial maximum kinetic energy of a single piece of shrapnel will be related to the mass of the shrapnel since the kinetic energy of an individual piece of mass mm is mv22mv22. The total maximum initial kinetic energy of the shrapnel pieces will be the sum of the kinetic energies of the individual pieces.

 

The third bullet point provides some sort of speed. And that, of course, is also related to kinetic energy. But it is not clear exactly what the "detonation speed" means. So I'm not sure what to do with it.

 

In conclusion, here are the main questions that, in my opinion, need to be answered in order to answer your question.

 

What is the total energy released in the explosion of the grenade?

 

What percentage of the total is in the form of heat?

 

Although there is also sound energy released, it is usually so small compared to the other forms, it can be ignored.

 

The total maximum initial kinetic energy of all of the pieces of shrapnel will equal the total energy released in the explosion minus the energy released in the form of heat. Then you can divide the total kinetic energy by 1000 to give you the average maximum initial kinetic energy of each piece. From that, given KE=mv22mv22, you can calculate the maximum average speed, vv, of each piece of shrapnel.

 

Since the maximum initial speed of the individual pieces will vary widely, there is no way of determining the maximum initial speed of an individual piece. Just the average of all the pieces.

 

UPDATE:

 

The following is an update based on the additional information you provided in comments.

 

Explosive mass is how much (mass-wise) of the explosive is in the grenade, in this case. The grenade, as a thing, weights a total of 400g. Of that weight, 180g is explosives (Composition B, to be precise), which leaves 220g as the weight of the metal(?) casing and coil of notched metal wire that forms the shrapnel after detonation

 

OK, based on this additional information we can say that the total mass of the pieces of shrapnel is 220 g instead of 180 g.

 

Detonation speed is, I think, the speed of the explosive reaction itself, or the shockwave it generates. One of the two (if they aren't the same). I don't know the technicallity of it; I just assume that that might be nescessary/useful to calculate how much energy is distributed to the shrapnel. Took that the M67 uses Composition B as it's explosive from it's wikipedia page, and then took the detonation speed of Composition B from it's wikipedia page

 

So now we have additional information on the energy released. I have read that when a blast shock wave interacts with a medium (solid, liquid, or gas), the energy can be absorbed or transformed to kinetic energy of the medium that accelerates a body of a given mass to its stated velocity.

 

The following is my

 

reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3379975/

 

So it would seem that the total energy of the shock wave can be accounted for as being converted into the total kinetic energy of the pieces of shrapnel. But I'm not exactly sure of the connection between the speed of the shockwave, 8050 m/s, and the kinetic energy of the pieces of shrapnel. One possibility is that this speed is also the average speed of the pieces of shrapnel just after the explosion. If that were the case, then we would have the total kinetic energy of the pieces

 

KEtot=mv22KEtot=mv22

 

Where mm = 0.220 kg, and vv = 8050 m/s.

 

Then the average maximum average kinetic energy of each piece would be

 

KEeach=KEtot1000KEeach=KEtot1000

 

There are, admittedly, a lot of assumptions in this. But that's the best I can do.

There might be something very wrong with this approach. I'm coming up with just 3m/s for 1000 pieces of shrapnel, which should be close to, if not less than, what grenades like this should generate in shrapnel

 

I'm not sure why you are coming up with 3 m/s. If we assume the maximum velocity of each piece of shrapnel is the same as the velocity of the shock wave, 8050 m/s, and the mass of each pieces is 0.22 kg/1000 or 0.00022 kg, that gives each piece of shrapnel a kinetic energy of 7,128 Joules, or 7.13 kJ per piece of shrapnel.

 

Now I read that the explosives in your type of grenade is a combination of TNT and RDX, and that RDX is even more "energetic" than TNT. But let's assume all 180 grams of your explosive mass is TNT. According to Wiki 1 gm of TNT is equivalent to 4.184 kJ. So 180 grams would be 753 kJ. Divide that by the 1000 pieces you have 0.753 kJ per piece. That's only one order of magnitude different than the 7.13 kJ per piece estimate based on the assumption that the max velocity of each piece equals the shock wave velocity. Given all the assumptions and other unknowns, I'd say that wasn't too bad!

 

At any rate, I hope this helps.

 

Disregarding the points of confusion on nomenclature, the speed of the shrapnel is assumed to be uniform (I'm disconsidering irregularity in shapes, masses, etc), so the average initial velocity is the actual initial velocity in this case. --- Sound = shockwave. And since the shrapnel bits of the grenade are on the outside of the explosive, I assume whatever sound happens is after the shrapnel has already been accelerated, and is generated by the shrapnel's air-resistance. – XenoRo Sep 6 '19 at 23:07

 

The two questions are absolutelly right. And the formula for KE is exactly what I need once those are answered. I guess the question then becomes "How do I calculate how much energy is released from a certain explosive mass that has a certain detonation speed? And how much of that is heat?" -

 

I am not sure I can find sources for heat/kinectic-efficiency of the Composition B explosive, so unless you have a formula (which I feel this kind of thing is too material-dependent to have a formula; but hey, hope should die last), let's disconsider that as well, and go with just total energy. – XenoRo Sep 6 '19 at 23:07 

 

Yep, already found some useful stuff to determine energy from explosive. The wikipedia page on TNT Equivalence has both energy-density of TNT ("for each gram of TNT exploded, 4184 joules of energy are released.") and CompositionB's "Relative effectiveness factor" compared to TNT (1.33). So 1 gram of CompB should yield 5564.72 joules of energy. Now, disregarding loss to heat, do I just plug that in the KE formula, rearange for finding V, and solve? Is KE in joules in the formula? – XenoRo Sep 6 '19 at 23:18

 

@XenoRo Yes the kinetic energy is in joules if you use m/s for velocity and kg for mass in the equations I gave you. – Bob D Sep 6 '19 at 23:30

 

There might be something very wrong with this approach. I'm coming up with just 3m/s for 1000 pieces of shrapnel, which should be close to, if not less than, what grenades like this should generate in shrapnel – XenoRo Sep 7 '19 at 1:05

 

@XenoRo Not sure how you came up with 3 m/s. I was thinking we would assume the max velocity of each piece of shrapnel might be the same as the velocity of the shock wave. And using that assumption doesn't seem to be all that bad if you do the calculations. See the additional update to my answer. – Bob D Sep 7 '19 at 2:02

 

Behold my incompetence at math: So, the KE equation is Ke=mv22Ke=mv22, right? Rearranging to make v the subject: 2Ke=mv22Ke=mv2 to 2Kem=v22Kem=v2 to 2Kem−−−√=v2Kem=v and resulting formula v=2Kem−−−√v=2Kem (Is this correct? I really suck at algebra and math in general) --- With 180g of TNT times 1.33 of the efficiency of CompB, we get 1001649.6 J. Plugging the data in, we get v=1001649.60.22−−−−−−√v=1001649.60.22, which results in 2133.76491847 (oh no that's even less than last time). Div by 1000 = 2.13376491847 m/s – XenoRo Sep 7 '19 at 4:18 

 

Holy crap, I'm an idiot. The formula is v=Kem2−−−√v=Kem2. But result is what I got before, 3017.59928661, which after division by 1000 is 3.01759928661. – XenoRo Sep 7 '19 at 4:32

 

Ohhhhh! I'm a double idiot! Mistake number one: 2 comments above was not multiplying the Ke by 2; since I rearranged the formula with as 2Ke, rather than m/2. Forgot that multiplication by 2 when solving. --- Aaaand mistake number two: Don't divide the final answer by 1000, silly me! The Ke is 1/1000, but so is the mass! You are not dealing with the Ke anymore, you are dealing with v, me! The 3000~ m/s is already the answer for individual shrapnel pieces (too)! – XenoRo Sep 7 '19 at 4:56 

 

@exman I'm thinking the OP meant the maximum velocity shortly after the explosion and before the fragments encounter air resistance. But that's just a guess. – Bob D Sep 6 '19 at 20:21

 

Can we get some definitions. What is the explosive mass? Is it the total mass of the 1000 pieces of shrapnel? What is meant by "explosive detonation speed" (composition B)? – Bob D Sep 6 '19 at 20:24

 

@BobD You guessed correctly. Guys, I'm not a physicist; I am not too aware of deep technicalities in physics nomenclature. I'm just trying to understand how to get the speed of projectiles/shrapnel from an explosive. Please help me help you help me by not over-complicating things! lol – XenoRo Sep 6 '19 at 21:16

 

@XenoRo Thanks for the further explanation. I posted my answer before seeing it. I will update my answer based on your additional explanation. – Bob D Sep 6 '19 at 22:51

 

When you say "initial speed" I will assume you mean the maximum speed of a single shrapnel piece.

 

Regarding the three bullet points:

 

The first bullet point, in my opinion, is of no help. This is the mass that simply falls to the ground (the local remnants of the grenade). It probably accounts for some of the energy of the explosion since the pieces will obviously be hot. But I suspect it accounts for very little.

 

If the second bullet point gives us the total mass of the 1000 shrapnel pieces, it gives us one of the needed parameters to answer your question. The initial maximum kinetic energy of a single piece of shrapnel will be related to the mass of the shrapnel since the kinetic energy of an individual piece of mass mm is mv22mv22. The total maximum initial kinetic energy of the shrapnel pieces will be the sum of the kinetic energies of the individual pieces.

 

The third bullet point provides some sort of speed. And that, of course, is also related to kinetic energy. But it is not clear exactly what the "detonation speed" means. So I'm not sure what to do with it.

 

In conclusion, here are the main questions that, in my opinion, need to be answered in order to answer your question.

 

What is the total energy released in the explosion of the grenade?

 

What percentage of the total is in the form of heat?

 

Although there is also sound energy released, it is usually so small compared to the other forms, it can be ignored.

 

The total maximum initial kinetic energy of all of the pieces of shrapnel will equal the total energy released in the explosion minus the energy released in the form of heat. Then you can divide the total kinetic energy by 1000 to give you the average maximum initial kinetic energy of each piece. From that, given KE=mv22mv22, you can calculate the maximum average speed, vv, of each piece of shrapnel.

 

Since the maximum initial speed of the individual pieces will vary widely, there is no way of determining the maximum initial speed of an individual piece. Just the average of all the pieces.

 

UPDATE:

 

The following is an update based on the additional information you provided in comments.

 

Explosive mass is how much (mass-wise) of the explosive is in the grenade, in this case. The grenade, as a thing, weights a total of 400g. Of that weight, 180g is explosives (Composition B, to be precise), which leaves 220g as the weight of the metal(?) casing and coil of notched metal wire that forms the shrapnel after detonation

 

OK, based on this additional information we can say that the total mass of the pieces of shrapnel is 220 g instead of 180 g.

 

Detonation speed is, I think, the speed of the explosive reaction itself, or the shockwave it generates. One of the two (if they aren't the same). I don't know the technicallity of it; I just assume that that might be nescessary/useful to calculate how much energy is distributed to the shrapnel. Took that the M67 uses Composition B as it's explosive from it's wikipedia page, and then took the detonation speed of Composition B from it's wikipedia page

 

So now we have additional information on the energy released. I have read that when a blast shock wave interacts with a medium (solid, liquid, or gas), the energy can be absorbed or transformed to kinetic energy of the medium that accelerates a body of a given mass to its stated velocity.

 

The following is my reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3379975/

So it would seem that the total energy of the shock wave can be accounted for as being converted into the total kinetic energy of the pieces of shrapnel. But I'm not exactly sure of the connection between the speed of the shockwave, 8050 m/s, and the kinetic energy of the pieces of shrapnel. One possibility is that this speed is also the average speed of the pieces of shrapnel just after the explosion. If that were the case, then we would have the total kinetic energy of the pieces

 

KEtot=mv22KEtot=mv22

 

Where mm = 0.220 kg, and vv = 8050 m/s.

Then the average maximum average kinetic energy of each piece would be

KEeach=KEtot1000KEeach=KEtot1000

 

There are, admittedly, a lot of assumptions in this. But that's the best I can do.

 

There might be something very wrong with this approach. I'm coming up with just 3m/s for 1000 pieces of shrapnel, which should be close to, if not less than, what grenades like this should generate in shrapnel

 

I'm not sure why you are coming up with 3 m/s. If we assume the maximum velocity of each piece of shrapnel is the same as the velocity of the shock wave, 8050 m/s, and the mass of each pieces is 0.22 kg/1000 or 0.00022 kg, that gives each piece of shrapnel a kinetic energy of 7,128 Joules, or 7.13 kJ per piece of shrapnel.

 

Now I read that the explosives in your type of grenade is a combination of TNT and RDX, and that RDX is even more "energetic" than TNT. But let's assume all 180 grams of your explosive mass is TNT. According to Wiki 1 gm of TNT is equivalent to 4.184 kJ. So 180 grams would be 753 kJ. Divide that by the 1000 pieces you have 0.753 kJ per piece. That's only one order of magnitude different than the 7.13 kJ per piece estimate based on the assumption that the max velocity of each piece equals the shock wave velocity. Given all the assumptions and other unknowns, I'd say that wasn't too bad!

 

At any rate, I hope this helps.

 

Bob: exman regarding the points of confusion on nomenclature, the speed of the shrapnel is assumed to be uniform (I'm disconsidering irregularity in shapes, masses, etc), so the average initial velocity is the actual initial velocity in this case. --- Sound = shockwave. And since the shrapnel bits of the grenade are on the outside of the explosive, I assume whatever sound happens is after the shrapnel has already been accelerated, and is generated by the shrapnel's air-resistance.

 

The two questions are absolutelly right. And the formula for KE is exactly what I need once those are answered. I guess the question then becomes "How do I calculate how much energy is released from a certain explosive mass that has a certain detonation speed? And how much of that is heat?" - I am not sure I can find sources for heat/kinectic-efficiency of the Composition B explosive, so unless you have a formula (which I feel this kind of thing is too material-dependent to have a formula; but hey, hope should die last), let's disconsider that as well, and go with just total energy. 

 

Yep, already found some useful stuff to determine energy from explosive. The wikipedia page on TNT Equivalence has both energy-density of TNT ("for each gram of TNT exploded, 4184 joules of energy are released.") and CompositionB's "Relative effectiveness factor" compared to TNT (1.33). So 1 gram of CompB should yield 5564.72 joules of energy. Now, disregarding loss to heat, do I just plug that in the KE formula, rearange for finding V, and solve? Is KE in joules in the formula? – exman Sep 6 '19 at 23:18

 

@ exman Yes the kinetic energy is in joules if you use m/s for velocity and kg for mass in the equations I gave you. – Bob D Sep 6 '19 at 23:30

There might be something very wrong with this approach. I'm coming up with just 3m/s for 1000 pieces of shrapnel, which should be close to, if not less than, what grenades like this should generate in shrapnel – exman Sep 7 '19 at 1:05

 

 

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  • 3 months later...

exman...can you believe this guy put a meme about why is is proud to be a (Asian) Indian because of these accomplishments and some fruit cake posted this to it:

 

It was the Persians that invented chess it was the Mayans that invented the zero it was the English that invented shampoo which was made from whale blubber it was the Mexicans the first started using Ink from squid. Who is coming up with these Facts ?

 

Of the top of my head:

 

First off the the exact origins of chess are unknow BUT the accept theory is the Indians are credited with perfecting it's begins and I believe making standard rules. (which I guess would be perfecting it) They were the ones who spread it thru the world.

 

The zero...came from East Africa or the Middle East.

 

Who invented shampoo...how can you date that ?

 

The Mexicans were the first to start ink...the guy has to KIDDING !

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