rasmack 0 #51 March 4, 2005 Quote It is impoper to say that something has more inertia than something else. Momentum and Kinetic energy can be thought of that way, but not inertia. As we are talking about linear motion, one would normally consider "inertia" = "inertial mass" which is certainly a constant, unless you regularly pee your pants on your way down. As for terminal velocity, it was covered pretty thoroughly in this thread: http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=1458775;page=1;sb=post_latest_reply;so=ASC;mh=25;HF #682, Team Dirty Sanchez #227 “I simply hate, detest, loathe, despise, and abhor redundancy.” - Not quite Oscar Wilde... Quote Share this post Link to post Share on other sites
sirenoremac 0 #52 March 4, 2005 Nobody said inertia was a constant. However the inertia of any given body is constant. It is simply not a constant in the sense that C is a constant or pi is a constant. Just like mass, it remains constant for any given body. That is, assuming the body isn't intrinsically changing, as in gaining mass or losing mass. Quote Share this post Link to post Share on other sites
mjosparky 3 #53 March 4, 2005 You are all wrong. "Terminal Velocity" has nothing to do with physics. It was a movie that came out several years ago and gave skydiving a bad name. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
rasmack 0 #54 March 4, 2005 Yes. Terrible movie. "Cutaway" on the other hand... HF #682, Team Dirty Sanchez #227 “I simply hate, detest, loathe, despise, and abhor redundancy.” - Not quite Oscar Wilde... Quote Share this post Link to post Share on other sites
sundevil777 93 #55 March 4, 2005 Quoteyou're wrong my friend...inertia is not a constant. From Websters dictionary: a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force I don't think there is a formula for an objects inertia. In what units is inertia measured? Inertia is not momentum, it is not mass.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites
rasmack 0 #56 March 4, 2005 From Knudsen & Hjorth, Elements of Newtonian Mechanics, 3rd ed., p. 27: QuoteMomentum is the product of the velocity of a body and the amount of matter the body contains. That amount of matter is called the mass of the body and is a measure of its inertia. Instead of "mass" we shall occasionally use the more precise term "inertial mass" EDIT: I should add that inertia and mass are identical up to a multiplicative constant that can be (and is) absorbed into the definition of the constant of gravitation.HF #682, Team Dirty Sanchez #227 “I simply hate, detest, loathe, despise, and abhor redundancy.” - Not quite Oscar Wilde... Quote Share this post Link to post Share on other sites
rehmwa 2 #57 March 4, 2005 QuoteQuoteIf I whirl an object around on a string, there is most definitely a measurable outwardly directed force on the anchor point of the string, as well as a measurable tension in the string. Any force measuring device, such as a load cell, is capable of recording it. Newton's 3rd law requires that it exist as a reaction to the centripetal force acting on the object moving in a circle. Calling it "centrifugal" is as good a name as any. I don't disagree with you, but as you correctly point out, that outward force is on the anchor point in the center, and most people who use the term "centrifugal" apply it to the object that is rotating. Put your load cell anywhere on the string (not just at the anchor point in the center - even at the string to anchor point of the object). Tell me what it reads......(John wrote tension in the string so I'm not correcting that or anything presumptious like that). Just equal and opposite discussion - call it what you want - centripetal, centrifugal, arnie, arapaho, marriage - a rose by any other name. ... Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants Quote Share this post Link to post Share on other sites
larsrulz 0 #58 March 4, 2005 QuoteMy point was that it would cancel in relating two objects. Just a technicality really. You could do it either way, but gravity is a constant that would be in the equation for both objects, so it can be cancelled. Gravity definitely is necessary for determining terminal velocity, even if it isn't necessary for determining the ratio between two objects. Like others have said, a body at terminal in freefall with be at the speed in which "lift" (the drag force) is equal to the weight of the body. Different bodies end up with different drag forces, which is why terminal velocity varies slightly between people (sometimes significantly). This is equally due to the mass difference as it is to the different body surface areas and slickness of suit. The link to another thread above covers two different ways of going about determining terminal velocity, but I still disagree with one of them. I got a strong urge to fly, but I got no where to fly to. -PF Quote Share this post Link to post Share on other sites
kelpdiver 2 #59 March 4, 2005 Quote*** The object in question is being accelerated from 0 to terminal velocity! Quote Maybe I misunderstood the question but what I gathered from it was the person was asking about weight vests and the physical principle behind why they can be used to help two jumpers attain similar terminal velocities. Because he did not specify someone using these weight vests to B.A.S.E. jump off of bridges or hovering helicopters I just assumed he was talking about jumping out of airplanes . If it is airplanes he is talking about jumping out of, you are not accelerating from 0-120. With respects to terminal velocity, yes you are. While I'm sure there are slight differences on how the person flies on the hill, the effect of gravity has essentially the same curve for a helicoptor jump or someone exiting a King Air. The horizonal element is gone within 10-15s of freefall. Weight vests do the job because they increase the force of gravity without increasing the opposing force of drag. A higher terminal speed can be achieved. On the other end for a big guy like me- a pile sweater increases drag significantly, while barely altering the force of gravity. My fall rate drops. Quote Share this post Link to post Share on other sites mjosparky 3 #60 March 4, 2005 QuoteYes. Terrible movie. "Cutaway" on the other hand... Was another terrible movie. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites sundevil777 93 #61 March 5, 2005 QuoteFrom Knudsen & Hjorth, Elements of Newtonian Mechanics, 3rd ed., p. 27: QuoteMomentum is the product of the velocity of a body and the amount of matter the body contains. That amount of matter is called the mass of the body and is a measure of its inertia. Instead of "mass" we shall occasionally use the more precise term "inertial mass" EDIT: I should add that inertia and mass are identical up to a multiplicative constant that can be (and is) absorbed into the definition of the constant of gravitation. So, what are the units of inertia? If mass is a measure of it, then there is a formula, right? Please tell us more about multiplicative constants and absorbtion into the gravitational constant. Your reference is a bit vague about the definition of inertia. Can you show any examples of how an object's inertia is used to calculate anything about the dyamics of a body in motion? I don't think it is.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites kallend 1,623 #62 March 5, 2005 QuoteQuoteFrom Knudsen & Hjorth, Elements of Newtonian Mechanics, 3rd ed., p. 27: QuoteMomentum is the product of the velocity of a body and the amount of matter the body contains. That amount of matter is called the mass of the body and is a measure of its inertia. Instead of "mass" we shall occasionally use the more precise term "inertial mass" EDIT: I should add that inertia and mass are identical up to a multiplicative constant that can be (and is) absorbed into the definition of the constant of gravitation. So, what are the units of inertia? If mass is a measure of it, then there is a formula, right? Please tell us more about multiplicative constants and absorbtion into the gravitational constant. Your reference is a bit vague about the definition of inertia. Can you show any examples of how an object's inertia is used to calculate anything about the dyamics of a body in motion? I don't think it is. Doesn't phlogiston come into it somewhere?... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites pilotdave 0 #63 March 5, 2005 Inertia is the concept of an object's resistance to change in motion. The formula that defines it is F=ma. Mass is the measure of inertia. Higher mass requires higher force to accelerate. This is just kinematics, not dynamics...though that's the same. Rotational inertia (moments of inertia) comes into play in dynamics. Dunno what the rest of it is about. Dave Quote Share this post Link to post Share on other sites larsrulz 0 #64 March 5, 2005 QuoteDoesn't phlogiston come into it somewhere? I think ash dives have shown this not to be true. I got a strong urge to fly, but I got no where to fly to. -PF Quote Share this post Link to post Share on other sites sundevil777 93 #65 March 5, 2005 QuoteQuoteInertia is the concept That is right, a concept. An object that has mass must be shoved with a force to accelerate it. The formula that defines it is F=ma. Mass is the measure of inertia.Quote An object's inertial mass is the same as what is normally just called, mass. But to say that inertia = mass is incorrect. The term rotational inertia does not = inertia. There is a formula for the rotational inertia of an object, it depends on how the mass is distributed about the axis of rotation, so it can be different for objects of the same mass. There are formulas for the area moment of inertia, but this stress mechanics term doesn't even involve the mass of an object. Inertia is a concept. It is not = mass.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites mjosparky 3 #66 March 5, 2005 Reading this thread makes my hear hurt. I need to lay down. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites Zep 0 #67 March 5, 2005 You go an lie down, The rest of you keep going; I'm waiting for the really interesting part when it turns to BRUTE force, that I'll be able to understand. Oh and Mr Kallend I cant help wondering if your wonderful sence of humour is'nt a by product of your Cambridge days. Gone fishing Quote Share this post Link to post Share on other sites kallend 1,623 #68 March 5, 2005 Quote You go an lie down, The rest of you keep going; I'm waiting for the really interesting part when it turns to BRUTE force, that I'll be able to understand. Oh and Mr Kallend I cant help wondering if your wonderful sence of humour is'nt a by product of your Cambridge days. Umm - well, I was a contemporary of Eric Idle, and a couple of years behind John Cleese. Also a contemporary of (and knew) Hawking, not known for his humor but quite funny anyway. I think about 90% of the Beeb's light entertainment people came through Cambridge. Must be something in the water (if you fell in the river while rowing, they'd rush you to hospital and pump your stomach).... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites kallend 1,623 #69 March 5, 2005 Very nice description of the inertia tensor here. .... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites sundevil777 93 #70 March 5, 2005 Did you see what Tracy Ullman did with Steven Hawking? They did a skit where he left his wife to live with an admiring student/intern, and then she gets tired of him because he's a pain in the ass.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites Avion 0 #71 March 6, 2005 QuoteIn what units is inertia measured? Inertia is a function of mass. An objects Inertia varies in direct proportion with its mass. For all practal purposes units of mass may be considered as units of inertia. Inertia is mass' resistance to change in either speed or direction. Due to this property mass can store energy. Energy stored in this fashion is refered to as Kinetic Energy, KE, which is mass times velocity squared. Momentum is mass times velocity. Momentum is generally what Johnny Jumper would consider to be inertia, and what Shooter Shaun would consider to be the knock down power of a bullet. Kinetic energy is what scientists use to determine the trajectories of ballastic objects and such. Quote Share this post Link to post Share on other sites NoShitThereIWas 0 #72 March 10, 2005 Okay, I see your point also. I am going to go take an aspirin now. Roy Bacon: "Elvises, light your fires." Sting: "Be yourself no matter what they say." Quote Share this post Link to post Share on other sites kallend 1,623 #73 March 10, 2005 Quote*** Momentum is generally what Johnny Jumper would consider to be inertia, and what Shooter Shaun would consider to be the knock down power of a bullet. Kinetic energy is what scientists use to determine the trajectories of ballastic objects and such. "Knock down power" is kinetic energy, not momentum. If it were momentum, both the shooter and the target would suffer equally. KE is not used to determine trajectories.... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites Avion 0 #74 March 10, 2005 From the general information on small arms ballastics I have read in relation to target shooting and hunting. Momentum seems to be the more accepted indicater of knock down power. A high pressure 9mm round will have more kinetic energy than a regular 45 ACP, although the 45 will most likely knock the person over who get tagged by one, knocking someone over with a 9mm is less likely, according to the old guys at the range I go to. The weight of a 45 round is around twice that of the 9mm. This is an area where practical results differ from what science would expect. The study of small arms reveals a number of these unexpected peculararities. Hunters, LEOs, and the military have noticed this is the case through actual experience, rather than through scientific prediction. Quote Share this post Link to post Share on other sites darkwing 4 #75 March 10, 2005 Quote... This is an area where practical results differ from what science would expect. The study of small arms reveals a number of these unexpected peculararities. Hunters, LEOs, and the military have noticed this is the case through actual experience, rather than through scientific prediction. I say that if practical results differ from the science, then the people "using" the science aren't very good at what they are doing. They need to study more science. Just becuase people claim (overtly or otherwise) that science doesn't work, doesn't mean the science is bad, it just means they are. -- Jeff My Skydiving History Quote Share this post Link to post Share on other sites Prev 1 2 3 4 Next Page 3 of 4 Join the conversation You can post now and register later. If you have an account, sign in now to post with your account. Note: Your post will require moderator approval before it will be visible. 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mjosparky 3 #60 March 4, 2005 QuoteYes. Terrible movie. "Cutaway" on the other hand... Was another terrible movie. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
sundevil777 93 #61 March 5, 2005 QuoteFrom Knudsen & Hjorth, Elements of Newtonian Mechanics, 3rd ed., p. 27: QuoteMomentum is the product of the velocity of a body and the amount of matter the body contains. That amount of matter is called the mass of the body and is a measure of its inertia. Instead of "mass" we shall occasionally use the more precise term "inertial mass" EDIT: I should add that inertia and mass are identical up to a multiplicative constant that can be (and is) absorbed into the definition of the constant of gravitation. So, what are the units of inertia? If mass is a measure of it, then there is a formula, right? Please tell us more about multiplicative constants and absorbtion into the gravitational constant. Your reference is a bit vague about the definition of inertia. Can you show any examples of how an object's inertia is used to calculate anything about the dyamics of a body in motion? I don't think it is.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites
kallend 1,623 #62 March 5, 2005 QuoteQuoteFrom Knudsen & Hjorth, Elements of Newtonian Mechanics, 3rd ed., p. 27: QuoteMomentum is the product of the velocity of a body and the amount of matter the body contains. That amount of matter is called the mass of the body and is a measure of its inertia. Instead of "mass" we shall occasionally use the more precise term "inertial mass" EDIT: I should add that inertia and mass are identical up to a multiplicative constant that can be (and is) absorbed into the definition of the constant of gravitation. So, what are the units of inertia? If mass is a measure of it, then there is a formula, right? Please tell us more about multiplicative constants and absorbtion into the gravitational constant. Your reference is a bit vague about the definition of inertia. Can you show any examples of how an object's inertia is used to calculate anything about the dyamics of a body in motion? I don't think it is. Doesn't phlogiston come into it somewhere?... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
pilotdave 0 #63 March 5, 2005 Inertia is the concept of an object's resistance to change in motion. The formula that defines it is F=ma. Mass is the measure of inertia. Higher mass requires higher force to accelerate. This is just kinematics, not dynamics...though that's the same. Rotational inertia (moments of inertia) comes into play in dynamics. Dunno what the rest of it is about. Dave Quote Share this post Link to post Share on other sites
larsrulz 0 #64 March 5, 2005 QuoteDoesn't phlogiston come into it somewhere? I think ash dives have shown this not to be true. I got a strong urge to fly, but I got no where to fly to. -PF Quote Share this post Link to post Share on other sites
sundevil777 93 #65 March 5, 2005 QuoteQuoteInertia is the concept That is right, a concept. An object that has mass must be shoved with a force to accelerate it. The formula that defines it is F=ma. Mass is the measure of inertia.Quote An object's inertial mass is the same as what is normally just called, mass. But to say that inertia = mass is incorrect. The term rotational inertia does not = inertia. There is a formula for the rotational inertia of an object, it depends on how the mass is distributed about the axis of rotation, so it can be different for objects of the same mass. There are formulas for the area moment of inertia, but this stress mechanics term doesn't even involve the mass of an object. Inertia is a concept. It is not = mass.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites mjosparky 3 #66 March 5, 2005 Reading this thread makes my hear hurt. I need to lay down. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites Zep 0 #67 March 5, 2005 You go an lie down, The rest of you keep going; I'm waiting for the really interesting part when it turns to BRUTE force, that I'll be able to understand. Oh and Mr Kallend I cant help wondering if your wonderful sence of humour is'nt a by product of your Cambridge days. Gone fishing Quote Share this post Link to post Share on other sites kallend 1,623 #68 March 5, 2005 Quote You go an lie down, The rest of you keep going; I'm waiting for the really interesting part when it turns to BRUTE force, that I'll be able to understand. Oh and Mr Kallend I cant help wondering if your wonderful sence of humour is'nt a by product of your Cambridge days. Umm - well, I was a contemporary of Eric Idle, and a couple of years behind John Cleese. Also a contemporary of (and knew) Hawking, not known for his humor but quite funny anyway. I think about 90% of the Beeb's light entertainment people came through Cambridge. Must be something in the water (if you fell in the river while rowing, they'd rush you to hospital and pump your stomach).... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites kallend 1,623 #69 March 5, 2005 Very nice description of the inertia tensor here. .... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites sundevil777 93 #70 March 5, 2005 Did you see what Tracy Ullman did with Steven Hawking? They did a skit where he left his wife to live with an admiring student/intern, and then she gets tired of him because he's a pain in the ass.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites Avion 0 #71 March 6, 2005 QuoteIn what units is inertia measured? Inertia is a function of mass. An objects Inertia varies in direct proportion with its mass. For all practal purposes units of mass may be considered as units of inertia. Inertia is mass' resistance to change in either speed or direction. Due to this property mass can store energy. Energy stored in this fashion is refered to as Kinetic Energy, KE, which is mass times velocity squared. Momentum is mass times velocity. Momentum is generally what Johnny Jumper would consider to be inertia, and what Shooter Shaun would consider to be the knock down power of a bullet. Kinetic energy is what scientists use to determine the trajectories of ballastic objects and such. Quote Share this post Link to post Share on other sites NoShitThereIWas 0 #72 March 10, 2005 Okay, I see your point also. I am going to go take an aspirin now. Roy Bacon: "Elvises, light your fires." Sting: "Be yourself no matter what they say." Quote Share this post Link to post Share on other sites kallend 1,623 #73 March 10, 2005 Quote*** Momentum is generally what Johnny Jumper would consider to be inertia, and what Shooter Shaun would consider to be the knock down power of a bullet. Kinetic energy is what scientists use to determine the trajectories of ballastic objects and such. "Knock down power" is kinetic energy, not momentum. If it were momentum, both the shooter and the target would suffer equally. KE is not used to determine trajectories.... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites Avion 0 #74 March 10, 2005 From the general information on small arms ballastics I have read in relation to target shooting and hunting. Momentum seems to be the more accepted indicater of knock down power. A high pressure 9mm round will have more kinetic energy than a regular 45 ACP, although the 45 will most likely knock the person over who get tagged by one, knocking someone over with a 9mm is less likely, according to the old guys at the range I go to. The weight of a 45 round is around twice that of the 9mm. This is an area where practical results differ from what science would expect. The study of small arms reveals a number of these unexpected peculararities. Hunters, LEOs, and the military have noticed this is the case through actual experience, rather than through scientific prediction. Quote Share this post Link to post Share on other sites darkwing 4 #75 March 10, 2005 Quote... This is an area where practical results differ from what science would expect. The study of small arms reveals a number of these unexpected peculararities. Hunters, LEOs, and the military have noticed this is the case through actual experience, rather than through scientific prediction. I say that if practical results differ from the science, then the people "using" the science aren't very good at what they are doing. They need to study more science. Just becuase people claim (overtly or otherwise) that science doesn't work, doesn't mean the science is bad, it just means they are. -- Jeff My Skydiving History Quote Share this post Link to post Share on other sites Prev 1 2 3 4 Next Page 3 of 4 Join the conversation You can post now and register later. If you have an account, sign in now to post with your account. Note: Your post will require moderator approval before it will be visible. Reply to this topic... × Pasted as rich text. Paste as plain text instead Only 75 emoji are allowed. × Your link has been automatically embedded. Display as a link instead × Your previous content has been restored. Clear editor × You cannot paste images directly. Upload or insert images from URL. Insert image from URL × Desktop Tablet Phone Submit Reply 0
mjosparky 3 #66 March 5, 2005 Reading this thread makes my hear hurt. I need to lay down. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
Zep 0 #67 March 5, 2005 You go an lie down, The rest of you keep going; I'm waiting for the really interesting part when it turns to BRUTE force, that I'll be able to understand. Oh and Mr Kallend I cant help wondering if your wonderful sence of humour is'nt a by product of your Cambridge days. Gone fishing Quote Share this post Link to post Share on other sites
kallend 1,623 #68 March 5, 2005 Quote You go an lie down, The rest of you keep going; I'm waiting for the really interesting part when it turns to BRUTE force, that I'll be able to understand. Oh and Mr Kallend I cant help wondering if your wonderful sence of humour is'nt a by product of your Cambridge days. Umm - well, I was a contemporary of Eric Idle, and a couple of years behind John Cleese. Also a contemporary of (and knew) Hawking, not known for his humor but quite funny anyway. I think about 90% of the Beeb's light entertainment people came through Cambridge. Must be something in the water (if you fell in the river while rowing, they'd rush you to hospital and pump your stomach).... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
kallend 1,623 #69 March 5, 2005 Very nice description of the inertia tensor here. .... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
sundevil777 93 #70 March 5, 2005 Did you see what Tracy Ullman did with Steven Hawking? They did a skit where he left his wife to live with an admiring student/intern, and then she gets tired of him because he's a pain in the ass.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites
Avion 0 #71 March 6, 2005 QuoteIn what units is inertia measured? Inertia is a function of mass. An objects Inertia varies in direct proportion with its mass. For all practal purposes units of mass may be considered as units of inertia. Inertia is mass' resistance to change in either speed or direction. Due to this property mass can store energy. Energy stored in this fashion is refered to as Kinetic Energy, KE, which is mass times velocity squared. Momentum is mass times velocity. Momentum is generally what Johnny Jumper would consider to be inertia, and what Shooter Shaun would consider to be the knock down power of a bullet. Kinetic energy is what scientists use to determine the trajectories of ballastic objects and such. Quote Share this post Link to post Share on other sites
NoShitThereIWas 0 #72 March 10, 2005 Okay, I see your point also. I am going to go take an aspirin now. Roy Bacon: "Elvises, light your fires." Sting: "Be yourself no matter what they say." Quote Share this post Link to post Share on other sites
kallend 1,623 #73 March 10, 2005 Quote*** Momentum is generally what Johnny Jumper would consider to be inertia, and what Shooter Shaun would consider to be the knock down power of a bullet. Kinetic energy is what scientists use to determine the trajectories of ballastic objects and such. "Knock down power" is kinetic energy, not momentum. If it were momentum, both the shooter and the target would suffer equally. KE is not used to determine trajectories.... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
Avion 0 #74 March 10, 2005 From the general information on small arms ballastics I have read in relation to target shooting and hunting. Momentum seems to be the more accepted indicater of knock down power. A high pressure 9mm round will have more kinetic energy than a regular 45 ACP, although the 45 will most likely knock the person over who get tagged by one, knocking someone over with a 9mm is less likely, according to the old guys at the range I go to. The weight of a 45 round is around twice that of the 9mm. This is an area where practical results differ from what science would expect. The study of small arms reveals a number of these unexpected peculararities. Hunters, LEOs, and the military have noticed this is the case through actual experience, rather than through scientific prediction. Quote Share this post Link to post Share on other sites
darkwing 4 #75 March 10, 2005 Quote... This is an area where practical results differ from what science would expect. The study of small arms reveals a number of these unexpected peculararities. Hunters, LEOs, and the military have noticed this is the case through actual experience, rather than through scientific prediction. I say that if practical results differ from the science, then the people "using" the science aren't very good at what they are doing. They need to study more science. Just becuase people claim (overtly or otherwise) that science doesn't work, doesn't mean the science is bad, it just means they are. -- Jeff My Skydiving History Quote Share this post Link to post Share on other sites
