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The message
from "Harold Walker" contains these words: Last time there was 2002...next time will be 2005....what is also fun to watch is the coyote trying to catch a grey squirrel...so far we have not seen any success story...altho when going thru the woods at the back of the house we see coyote feces with grey hair mixed in...an obvious sign of success....we dont have a stray cat problem as the coyotes like them too much...H Our bull terrier (back in the '50s) caught and killed a grey squirrel within a couple of feet of a Douglas fir. -- Rusty Open the creaking gate to make a horrid.squeak, then lower the foobar. http://www.users.zetnet.co.uk/hi-fi/ |
The message
from "BAC" contains these words: That's .22 short, I assume? .22 long is almost always supersonic. The difference other than speed between .22 firearms and .22 air rifles are that the bullet is c. 7 times heavier than the pellet, so a .22 bullet carries c. 14 times the energy of a .177 pellet at the same speed. Don't want to appear pedantic, but isn't the formula for kinetic energy 1/2 mv2? So if v is the same for two projectiles, the energy will vary by half the mass ratio, hence in your example it would be 3.5 times not 14 times? Apologies if incorrect :-) Yes, that is the formula, but you halve both weights and the ratio remains the same. Only varying the velocity upsets the linearity, which is why you have to be careful with an airgun which is on the limit for power: use a lighter pellet and the speed increases, so the kinetic energy will decrease in direct proportion to the mass of the pellet, but it will increase in proportion to the square of the velocity. Overdo it, and the increase in velocity can take the kinetic energy over that lost by reducing the pellet's weight, and render the gun illegal. If ever the Dibble want to test your airgun, be sure to stipulate which pellet you are using, and insist that they use the same for the test. I wouldn't put it past some smart-alec to have a supply of very light pellets... -- Rusty Open the creaking gate to make a horrid.squeak, then lower the foobar. http://www.users.zetnet.co.uk/hi-fi/ |
The message
from Tone contains these words: On Fri, 13 May 2005 04:30:44 -0400, "Harold Walker" wrote: Me thinks we are talking apples versus oranges......1000fps for an air gun is quite fast....yes, a tad below supersonic but still fast enough to give very little warning to the recipient at air gun range. Pray tell me, what model air gun gives a mv of greater than 4k fps....H But that velocity is illegal in the UK Chapter and verse, please? -- Rusty Open the creaking gate to make a horrid.squeak, then lower the foobar. http://www.users.zetnet.co.uk/hi-fi/ |
The message
from (Nick Maclaren) contains these words: In article , Jaques d'Alltrades writes: | | A foot pound is very precise, and is that amount of energy required to | shift the mass of one pound the distance of one foot - but how you would | measure it in the 'back garden lab' I don't know. Er, you DID learn some elementary physics at school, didn't you? I did 'A'-level physics when it was an exam... Moving a mass of a pound the distance of a foot isn't a measure of energy. At a naive guess, it would mean a foot-pound(force), a.k.a. a foot-poundall, or a foot-pound(weight). But another, equally important, question is how it is specified to be measured (which is where my remark about BHP comes in). If you drop a pound weight (weighed in air) the distance of one foot, it will dissipate one foot pound of energy when it comes to rest. Accordingly, if you raise a pound weight the distance of one foot, tou have to apply one foot pound of energy to accomplish it. However, if you are doing delicate measurements, you need to eliminate buoyancy, air resistance and friction, hence my reference to mass. I would have no difficulty measuring it at home, in any of several different ways, Well, I wouldn't be quite so sanguine, unless I had access to a lot more bits and bobs than I do. and how to do so would make a nice open elementary physics examination question. No, I don't approve of the modern approach of close examination questions or, worse, box ticking. Nor do I. Without any study I 'passed' a trial RAE (Rajo Amateur Exam) just by discarding answers which were impossible, and choosing the most likely of what was left. OK, I wouldn't have got a distinction, but it was by no means a scrape-in. -- Rusty Open the creaking gate to make a horrid.squeak, then lower the foobar. http://www.users.zetnet.co.uk/hi-fi/ |
The message
from Chris Bacon contains these words: Nick Maclaren wrote: Moving a mass of a pound the distance of a foot isn't a measure of energy. At a naive guess, it would mean a foot-pound(force), a.k.a. a foot-poundall, or a foot-pound(weight). But another, equally important, question is how it is specified to be measured (which is where my remark about BHP comes in). What's the difficulty with BHP? Almost self-explanatory. Yes, I thought I'd leave that for later. I think Nick must mean 'horsepower', which used to be measured by the length of stroke of the piston(s). -- Rusty Open the creaking gate to make a horrid.squeak, then lower the foobar. http://www.users.zetnet.co.uk/hi-fi/ |
The message
from (Nick Maclaren) contains these words: A long time ago, the legislators defined it in a way that made no engineering sense, and it created chaos in the UK car industry for many decades. Yes, 'real' BHP is a clear unit, but real foot-pounds is not a measure of energy. And it is what the relevant law means by the term, not what engineers do, that matters. Foot pounds is also a very precise measure of energy. -- Rusty Open the creaking gate to make a horrid.squeak, then lower the foobar. http://www.users.zetnet.co.uk/hi-fi/ |
wrote in message ... Chris Bacon wrote: Nick Maclaren wrote: A long time ago, the legislators defined it in a way that made no engineering sense, and it created chaos in the UK car industry for many decades. Yes, 'real' BHP is a clear unit Erm, are you saying that "the legislators" defined the "BHP" as a different size to an "ordinary" HP? They defined an "RAC HP" which was specified by the shape and size of the engine (cylinders), thus car makers in this country tended to develop long stroke, low-revving engines. The "Austin 7" was 7 of these funny HP, not 7BHP. The French used to have an idiosyncratic, non BHP, 'horsepower', too, hence the Citroen 2CV (deux chevaux, I think) and the Renault 4CV, both of which had slightly more BHP than their names might imply (but not much!). |
The message
from Chris Bacon contains these words: Nick Maclaren wrote: A long time ago, the legislators defined it in a way that made no engineering sense, and it created chaos in the UK car industry for many decades. Yes, 'real' BHP is a clear unit Erm, are you saying that "the legislators" defined the "BHP" as a different size to an "ordinary" HP? Legislators defined 'horsepower' in such a way that it was easy to produce vehicles with a lot more power than their nominal HP. This resulted in longer and longer strokes, and engines which were slow in rpm, but high in bottom-end grunt. (The first Jaguar was a case in point.) This had the effect of retarding engine development in the UK as it was not easy to accommodate overhead valves. Rover got over that with the 'inlet over exhaust' layout, but it still meant a slow-revving low compression engine. -- Rusty Open the creaking gate to make a horrid.squeak, then lower the foobar. http://www.users.zetnet.co.uk/hi-fi/ |
In article , Jaques d'Alltrades writes: | | If you drop a pound weight (weighed in air) the distance of one foot, it | will dissipate one foot pound of energy when it comes to rest. That is a foot-pound(weight), not moving a pound mass a distance of a foot! | I would have no difficulty measuring it at home, in any of several | different ways, | | Well, I wouldn't be quite so sanguine, unless I had access to a lot more | bits and bobs than I do. Boggle. Hang a wooden ball of known weight on the end of a string, shoot the pellet into it, and measure how far it swings; that gives you the momentum. Align the barrel with a spirit level, and measure the dopy of height with distance; that gives you the velocity. The mass can be measured with kitchen scales, and you can correct well enough for air resistance (in the latter case, the former doesn't need it) using 120 MPH as the terminal velocity of a tumbling human. I could probably think of several other methods if I put my mind to it, but those should do as a start. Regards, Nick Maclaren. |
Yes
"JB" wrote in message ... On Wed, 11 May 2005 21:00:42 +0000 (UTC), "batgirl" wrote: I think you are the verminous one. How utterly vile. What are the creatures doing to deserve death? What kind of a world do we live in where we blast something we don't like into smithereens? You are the keeper of a small part of this beautiful earth, please treat everything in it with respect. Everything? Does that include every plant and every slug? JB |
The message
from (Nick Maclaren) contains these words: Boggle. Hang a wooden ball of known weight on the end of a string, shoot the pellet into it, and measure how far it swings; that gives you the momentum. No it doesn't, unless your piece of string is of infinite length. Align the barrel with a spirit level, and measure the dopy The what? of height with distance; that gives you the velocity. I've no idea what you mean. To get the velocity you have to measure both the distance and the time it takes for the pellet to travel that distance. Then you must allow for how much the pellet slows, or all you get is the mean velocity over a distance, and the power of the gun must be measured *AT* the muzzle, not halfway along any preselected distance. Since the slowing of a pellet is not linear over a distance, and the faster the pellet, the steeper the fall-off curve, you need to have a much more reliable method. The mass can be measured with kitchen scales, and you can correct well enough for air resistance (in the latter case, the former doesn't need it) using 120 MPH as the terminal velocity of a tumbling human. A (clothed) tumbling human doesn't have the smoothness of a pellet, nor does it have the density, both of which have some bearing on the terminal velocity. I could probably think of several other methods if I put my mind to it, but those should do as a start. I think you might start with one which would work... -- Rusty Open the creaking gate to make a horrid.squeak, then lower the foobar. http://www.users.zetnet.co.uk/hi-fi/ |
The message
from "batgirl" contains these words: Yes "JB" wrote in message ... On Wed, 11 May 2005 21:00:42 +0000 (UTC), "batgirl" wrote: I think you are the verminous one. How utterly vile. What are the creatures doing to deserve death? What kind of a world do we live in where we blast something we don't like into smithereens? You are the keeper of a small part of this beautiful earth, please treat everything in it with respect. Everything? Does that include every plant and every slug? Except top-posters. -- Rusty Open the creaking gate to make a horrid.squeak, then lower the foobar. http://www.users.zetnet.co.uk/hi-fi/ |
On Fri, 13 May 2005 18:34:49 +0000 (UTC), "batgirl"
wrote: "JB" wrote in message .. . On Wed, 11 May 2005 21:00:42 +0000 (UTC), "batgirl" wrote: I think you are the verminous one. How utterly vile. What are the creatures doing to deserve death? What kind of a world do we live in where we blast something we don't like into smithereens? You are the keeper of a small part of this beautiful earth, please treat everything in it with respect. Everything? Does that include every plant and every slug? JB Yes [top posting corrected] So you respect plants by allowing them to be eaten by slugs and you respect slugs by killing or starving them? The moment you picked up a spade to plant something you have chosen to kill something else. It is at best naive to believe that you are in some way exempt from the chains of cause and effect that exist in the rest of the universe. JB |
On Fri, 13 May 2005 20:48:55 +0100, Jaques d'Alltrades
wrote: I've no idea what you mean. To get the velocity you have to measure both the distance and the time it takes for the pellet to travel that distance. Not strictly true. As you can calculate how long it will take for an object to fall a set distance then you can measure the drop of the pellet over a known distance and from that calculate the time it took to travel that distance (NB that assumes that deceleration to to wind resistance is negliible, which it will be over short distances albeit that makes the measurement less accurate) JB |
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