On 28/10/2007 9:15 PM, Stephen A. Lawrence wrote: > > > Harry Veeder wrote: >> On 28/10/2007 11:41 AM, Stephen A. Lawrence wrote: >> >>> Speed is not power. Power is speed times force. >>> >>> Torque is not power. Power is rotational velocity times torque. >>> >>> A simple lever can produce more _force_ than is applied to it, and a >>> simple chain and gear drive -- such as on my bicycle -- can produce far >>> more _speed_ at the output (the wheel) than the input (my feet on the >>> pedals). >>> >>> What's more, a capacitor can produce far more _power_ out than _power_ >>> in ... but only for a little while. The interesting question isn't >>> whether the machine can produce a lot of "speed" or "torque" or "force" >>> or even "power" -- the question is whether total /energy/ out is larger >>> than total /energy/ in. >> >> Why is energy more important than power? > > Well, it's not exactly more important. But "energy" is what you pay > for, literally and figuratively; power is the /rate/ at which energy is > delivered. This is, perhaps, a somewhat technical and nit-picky point.
Energy is a commodity i.e. a social construct, because it can be bought and sold. Energy is derived from momentum, but momentum is not for sale because it wasn't created by man. Momentum is an aspect of creation, our common heritage. > From 1913 Webster: > Power (definition 8) (Mechanics) > The rate at which mechanical energy is exerted or > mechanical work performed, as by an engine or other > machine, or an animal, working continuously; as, an > engine of twenty horse power. > > So, for instance, a lump of coal contains a particular, fixed amount of > chemical /energy/. The amount of /power/ delivered by burning the coal, > on the other hand, will depend on how fast it's burned. Similarly, gas > companies typically charge for the total number of (potential) BTU's > worth of gas they deliver during a month, which is a measure of energy, > rather than the rate at which you sucked the stuff up on particular days > during the month, which would be a measure of the peak power you used. > > Many of us, myself included, tend to be sloppy about it and use the > terms almost interchangeably. Often, it doesn't matter. In a case like > Ron Stiffler's circuit, for example, it's not something worth worrying > about: Instant by instant, either his circuit is producing no more > /power/ than it's consuming, or something very interesting is happening. > But the reason there's no issue of energy versus power in his circuit > is because there are no components in the circuit which can store more > than miniscule amounts of energy. Energy going in immediately comes > back out, and all energy coming out would be expected to be energy which > went in mere microseconds before. > > In the case of a large engine with a heavy flywheel, or anything which > contains batteries with large capacity, on the other hand, the > difference is vital. You can spin up the flywheel over a long period of > time, using little /power/ but a lot of energy (because the power is > applied for a long time), and then slow it down all at once, and get > back the same energy you put in far, far faster in a great burst of high > /power/ output. In the case of batteries -- the notorious lead-acid > batteries, in particular -- it's possible for the batteries to produce > power out, with no power in, for a long time. But, unless the total > /energy/ drawn from the batteries exceeds the total /energy/ which was > originally put into them, both in the form of chemical energy during > their assembly and in the form of electrical energy as they were > charged, there may be no indication of an over-unity process involved. I am more concerned with the reflexive habit of characterising power in terms of energy, then I am with with Mr. Neuman's machine. > >> >> Consider this hypothetical system: >> >> >> input power ---> gross output power out ---> net output power >> | | >> | | >> | | >> ------<------------ >> >> >> If the net output power exceeds the input power doesn't this qualify as >> "over unity"? > > It may, or it may not. It depends on whether the system can keep it up > indefinitely -- and that, in turn, depends on whether there's any kind > of energy storage device within the system itself, and that depends on > where you "draw the line" around the system -- i.e., it depends on what > you include within the system. "Drawing the line" is act of inclusion AND exclusion. OU systems exclude energy storage systems. A sincere and skilled OU inventor will take pains to exclude energy storage devices as components of his system. So unless you have reason to believe the inventor is a fraudster or is delusional, it is unfair presume a hidden store of energy in his system. > As I said, if the system includes a flywheel, storage batteries, or > large capacitors, then the peak output power can easily exceed the peak > input power, and it's necessary to look at the total energy budget over > the course of the run (from zero charge back to zero charge) to see if > it was over unity. If the system performed according to the flow chart, the maximal difference between output power to input power would be the salient measure. Pumping the system for power is an unfair methodology to asses whether the system is OU or not. > Another example is an automobile. During normal operation, the > automobile, viewed as a single system, produces large amounts of power > out, with no power in. But eventually the gas tank empties out. At > that point it's necessary to stop the car and refill it; during the > refilling, there's a large amount of (chemical) energy being added to > the system, and nothing being produced. Power-out/power-in for the > automobile varies enormously and is often far larger than 1, but the > ratio of total energy out to total energy in is no larger than 1. > > The automobile example also makes something else clear about this: It > depends on where you "draw the lines". If you can exclude all energy > storage devices from the system being tested, then you're back in a > situation where you can measure instantaneous power out and > instantaneous power in, and if the former is larger than the latter, > it's an OU situation. In particular, if you look just at the > automobile's _engine_, excluding both the gas tank and the battery, then > during constant-speed operation you would expect power-out to be no > larger than power-in, where power-in includes the rate at which chemical > energy is delivered from the gas tank through the fuel line. This is not a good way to think about OU because you are analysing a power system which you know was designed to work with energy storage devices. Harry
