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H. Humbert
SFN Die Hard
USA
4574 Posts |
 Posted - 01/31/2011 : 15:51:17 [Permalink]
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Originally posted by Dave W.
It's all about the distance between the mass and the ground. The path the mass takes to get there is irrelevant to the total kinetic energy available to put to work. |
I thought the spiral path would increase the distance the carriage must travel and thus increase the power generated, but you're saying that's incorrect. I guess because even if it takes longer path to the ground, it's traveling more slowly, so the total power output is the same? Do I have that right?
| So the screw-shaped path only figures in to how to get the energy out (a spinning magnet around a fixed coil would be a neat, if inefficient, idea!), and is irrelevant to the calculation of how much energy you can get. |
Thanks for saying my idea is neat, even if not particularly efficient. Obviously my knowledge of physics and electrodynamics doesn't even qualify as rudimentary, so I really appreciate these explanations.
Yeah, that's pretty much why people dropped the weights and cranks and stuff as soon as electricity was cheap and plentiful.
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And the era of cheap energy is almost over.  If the physical laws of this Universe were Intelligently Designed, then why is energy so tough to come by? |
"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
| Edited by - H. Humbert on 01/31/2011 17:23:58 |
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 01/31/2011 : 16:28:29 [Permalink]
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Originally posted by Dr. Mabuse
In both cases, the same amount of work has been done.
Almost anyway. The #2 task actually takes more energy, let's see if you can figure out where the rub lies. |
Um, the second task requires more distance? In both cases you require the same amount of energy to lift the beer and crate onto the table, but in the second example (because it requires several trips), you are expending additional energy on your way back. But wait, would you? If the movement is only up and down, floor to table, then the trip back down shouldn't cost any energy. Gravity does the work.
So...I don't know then. You've stymied me! 
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 01/31/2011 : 17:36:04 [Permalink]
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Originally posted by H. Humbert
I thought the spiral path would increase the distance the carriage must travel and thus increase the power generated, but you're saying that's incorrect. I guess because even if it takes longer to drop to the ground, it's falling slower, so the total power output is the same? Do I have that right? |
You've got it mostly right, now. Gravity only provides a force in one direction, so any movement in a different direction must come from some other force. Your carriage on a spiral track can be visualized as equivalent to an unpowered car on a long, not-very-steep hill. On a flat, the road actually provides an upward force equal and opposite to gravity's downward force, so that the car doesn't sink through the asphalt. On an incline, the direction of that upward force isn't straight up, and so the car starts rolling with a speed proportional to the steepness of the hill.
Now, if the tires of the car and the surface of the road were all friction-free, and the whole system were in a vacuum, then no matter what the angle of the hill, the car would always be going the same speed once it reached the bottom, and that speed would be the same speed as if you simply dropped the car from the same height as the hill. For ease of math, if the height of the hill were 4.9 meters, then the speed of the car would be 9.8 meters per second when it reaches the ground. If the hill is very steep, then the direction of that speed (the vector) will be mostly straight into the ground, and you'll wind up with lots of dented car parts. If the hill were very shallow, then the vector will also be nearly horizontal, and the car would just roll off the end of the ramp with a little bounce (but it might take hours to get there, instead of the one second it'd take for a car to drop the 4.9 meters).
Of course, we don't live in a friction-free vacuum. The reason real cars on real hills don't reach free-fall speeds is due to friction in the bearings, friction between the tires and road, and friction with the air. All of these things basically turn some of the gravitational kinetic energy into heat, and the longer the hill, the more time. Likewise, increasing the path length of the falling weight in a clock or lamp does nothing but increase the friction and thus lower the efficiency.
Because what these devices seek to do is turn the kinetic energy of a falling mass into electricity. Any of that kinetic energy that's turned into heat by friction cannot be turned into electricity.
The most efficient theoretical setup will be with a toothed vertical rod, and all of the falling mass touching that rod through a single gear, a gear which drives a dynamo or alternator to generate power. Of course such a system would be impossible since the gear would simply slip off the rod and free-fall, so in reality you'd need either multiple gears running mutliple dynamos, or some "idler" gears whose job is just to keep the main gear engaged, but the net effect of either is going to be reduced efficiency due to increased friction. Every contact point does. Making a huge, long, screw-shaped "hill" for the weight to fall down and spin around really does nothing more than add a lot of friction.| Thanks for saying my idea is neat, even if not particularly efficient. |
Most alternators spin magnets on the inside of a fixed loop of wire (for ease of construction and durability), and my first thought about your description was of a fixed loop of wire with magnets spinning around it - a sort of "inside-out" alternator. It'd be nifty to see work (and it would definitely work) even if it would have trouble lighting a room.
Basically, inside the corkscrew-shaped track for the magnets would need to be one or more fixed vertical rods on which a non-rotating carriage could slide down, holding several vertically-oriented coils of wire, their centers always at the same height as the middle of the magnets. From those coils you'd get AC power, which could easily be rectified to DC to light some LEDs.
Watch this video about making a simple electric motor. If you disconnect the battery, and instead spin the wire loop by hand, you'll get a pulsing DC current out of the wires where the battery used to be. Now instead, imagine that the loop of wire is fixed in the middle of the room, and you spun the whole table around it, and you'd get the same results. Well, get rid of the table so you're just spinning the magnets, and tweak a couple other little things, and you've created your setup (or at least the system I thought of after your initial description). | Obviously my knowledge of physics and electrodynamics doesn't even qualify as rudimentary, so I really appreciate these explanations. |
No sweat. It's fun to think about.| And the era of cheap energy is almost over. If the physical laws of this Universe were Intelligently Designed, then why is energy so tough to come by? |
Energy is easy to come by. Just burn some coal to heat water and run the steam through a turbine attached to an alternator. If coal isn't available, just burn whatever is handy (but you'll probably need more of it, on a pounds-per-watt basis, than coal). Cheap, cheap, cheap.
Oh... you probably meant cheap clean energy!  |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 01/31/2011 : 17:47:28 [Permalink]
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Originally posted by H. Humbert
Originally posted by Dave W.
To get one watt of power for an hour, you need about 367 kilogram-meters of weights. In other words, a mass of 367 kg falling one meter over the course of one hour will generate 1 watt given 100% efficiency of power conversion. |
Eeesh. Yeah, those figures are not encouraging. We'd need way more energy efficient machines. Maybe machines with biological components like muscle in them.
Ok, I think it's easier to use a smaller weight falling a further distance. My idea was to have a tall rod, maybe 10 feet tall say, cut spirally like a screw. A carriage could be set at the top of the rod and let to fall to the floor, spinning the whole time. Now, if the spinning carriage was fitted with magnets it could act as a turbine dynamo*, generating power that entire way down. (Obviously the grooves would need to be fairly frictionless so the carriage would slide to the floor using nothing but its own weight.) Once at the bottom, the carriage can be unlocked from the screw, slid to the top, and started down on its journey once again.
Would such a setup be capable of even powering an extremely efficient LED light source for a short time? If not, then I guess the idea is just flat out unworkable. I'm pretty discouraged after learning that the other gravity lamp doesn't work as advertised.
And thanks to everyone who clarified the function of pendulums.
* I'm not very sure of my terminology here.
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Biology is pretty inefficient in terms of energy. I forget the exact numbers, but there is a great deal of wasted energy in the formation of ATP.
If you back up to the source nutrient and the plant that made it, the numbers are worse.
What we need is a cheap and easily renewable source of energy. Fusion reactors or something.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 01/31/2011 : 17:52:56 [Permalink]
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Originally posted by Dave W.
Oh... you probably meant cheap clean energy!
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Yes. Actually, I guess I meant cheap, clean and renewable energy. The energy in coal ultimately comes from the sun and plant photosynthesis, which is a very slow process. It takes a lot of dead plant material and a heck of a long time to make coal. What do we do when there are no more fossil fuels? That's a long wait if we're going to rely on Nature to refill our gas tank, metaphorically speaking. I guess burning wood is pretty renewable. Do you think we would ever go back to the days of the steam engine?
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
| Edited by - H. Humbert on 01/31/2011 17:57:18 |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 01/31/2011 : 19:24:35 [Permalink]
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Originally posted by Dude
Biology is pretty inefficient in terms of energy. I forget the exact numbers, but there is a great deal of wasted energy in the formation of ATP. |
This page says that the strict efficiency of ATP alone is 38%, but that examining the whole chain from glucose down to energy use gives an efficiency of 50%.| If you back up to the source nutrient and the plant that made it, the numbers are worse. |
Wikipedia says that while the efficiency of an average leaf is about 5.4%, plants tend to waste a lot of that energy by doing silly things like growing roots, flowers, inedible stalks, etc., reducing efficiency down to less than half a percent for the plant parts humans use for energy. It says that sugarcane is an anomaly with a sunlight-to-product efficiency that peaks at 8%.
So assuming our bodies could actually burn about 10% of the sugar in raw sugarcane (assume losses due to harvesting, processing, digestion, conversion of fructose to glycogen and then into glucose, etc.), then the sunlight to sugarcane sugar to human cells to ATP to end-use efficiency is no more than about 0.4%, and much worse for other food crops.| What we need is a cheap and easily renewable source of energy. Fusion reactors or something. |
And then a mechanism to turn that energy into food, so we can forget about the uncertainties of farming. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 01/31/2011 : 20:12:30 [Permalink]
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Oh, and this:Originally posted by H. Humbert
Originally posted by Dr. Mabuse
In both cases, the same amount of work has been done.
Almost anyway. The #2 task actually takes more energy, let's see if you can figure out where the rub lies. |
Um, the second task requires more distance? In both cases you require the same amount of energy to lift the beer and crate onto the table, but in the second example (because it requires several trips), you are expending additional energy on your way back. But wait, would you? If the movement is only up and down, floor to table, then the trip back down shouldn't cost any energy. Gravity does the work. |
If you actually let gravity do the work, then to bend over you'd just go limp in the middle. People don't actually do that, they instead do - at best - a "controlled fall" and still fight gravity the whole way down.
Even if people just went limp in the middle, they don't tend to fold completely in half when bending over to pick something up (and they should use their knees, anyway), so they'd be exerting energy to stop the falling of the top half of their bodies at the correct height. Otherwise, bending over would result in a lot of black eyes as people allowed their faces to smack into their own knees just because they saw a dime on the ground.
Even if you didn't need to bend over, but just move your arms to move the beer, people don't lower their arms by just making the muscles go completely relaxed. You can do so, but it seems (to me, at least) to take a considerable act of will, since (I've just found out) letting one's arms fall from just shoulder height can generate enough energy to sting.
I know I can't just let my whole body go limp. There are some instincts I'm not willing to fight against, and what my body tries to do to protect myself from falling damage without conscious fore-thought seems pretty good to me. In fact, if you ever want to find out if someone is faking unconsciousness, just hold one of their hands a foot or so over their face and let go - unless they're really good at faking, they'll instinctively avoid slapping themselves in the face.
But that's getting really off-topic. The point is that even if you built a robot to move the beer, you wouldn't program it so that its grabber arm would come crashing down in free-fall to pick up the next six-pack. Too likely to damage the robot or, more importantly, the beer. So, you need to expend energy on both the up-swing and the down-swing, just much less on the latter than the former.
Even if you built a conveyor belt at an angle with pockets on it to hold the beer, such that it might seem that the downward trip of the belt is "free," energy-wise, it's still not because it's still generating friction with the air that must be overcome by the motors moving the belt. That wasted energy will be minuscule compared to the cost of lifting each six-pack, but it won't be zero. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 01/31/2011 : 21:51:11 [Permalink]
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Ok, free energy machine idea #2: It is my understanding that passing a magnet through a coiled wire produces electricity, correct? So if you had a tall tube of coiled wire and dropped a magnet straight down it, that should generate some amount of current, no? So if we could then devise a system where the magnet "falls" through a coil forever, wouldn't that produce unlimited energy?
Now, a satellite in orbit essentially free falls around the Earth. Replace the satellite with a magnet and build a massive tube of coiled wire around its path: Bingo! Unlimited energy.
Certainly there's no reason why this set up wouldn't work, right? 
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
| Edited by - H. Humbert on 01/31/2011 21:54:57 |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 01/31/2011 : 22:19:07 [Permalink]
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Originally posted by H. Humbert
Ok, free energy machine idea #2: It is my understanding that passing a magnet through a coiled wire produces electricity, correct? So if you had a tall tube of coiled wire and dropped a magnet straight down it, that should generate some amount of current, no? So if we could then devise a system where the magnet "falls" through a coil forever, wouldn't that produce unlimited energy?
Now, a satellite in orbit essentially free falls around the Earth. Replace the satellite with a magnet and build a massive tube of coiled wire around its path: Bingo! Unlimited energy.
Certainly there's no reason why this set up wouldn't work, right? |
Once you're in orbit, all you need is an electrodynamic tether to generate power, and a microwave transmission system to beam that power down to Earth.
In other words, you built (in your mind) the generator backwards again: the Earth's core is a huge magnet, so all you need to do is move a wire through the Earth's magnetic field to generate a current. It just needs to be a really long wire moving at pretty high speeds.
Unfortunately, as that Wikipedia article notes, the real-world experiments that have been performed have been failures. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dr. Mabuse
Septic Fiend
Sweden
9688 Posts |
Posted - 02/01/2011 : 11:16:34 [Permalink]
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Originally posted by H. Humbert
So...I don't know then. You've stymied me!
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The short of it is: Your exercising yourself by bending over and straightening yourself up 7 times more than in case #1. Your changing the height of your center of body mass, which requires work. 
Since we're not spring-loaded, we have no means of reclaiming the energy lost when we bend over, but have to generate new energy every time to straighten ourselves up.
When you lift something up, you are increasing the potential energy (in the gravity field). The formula is U=m*g*h and the simplest way to calculate it is to use ground as a relative zero point (or whatever is intended to be the final resting place). 'h' is the height in meters, 'm' is the mass in kilogram, and 'g' is the acceleration constant (which in metric system is ~9.81 m/s2. It varies a little depending on the distance from the equator, but we're talking about 0.1%)
It doesn't matter if it's a straight drop or a long slope (as in a spiral), the amount of energy in a specific object is directly proportional to the height above its final resting place.
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Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
Dr. Mabuse whisper.mp3
"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse
Support American Troops in Iraq:
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Dr. Mabuse
Septic Fiend
Sweden
9688 Posts |
Posted - 02/01/2011 : 11:33:12 [Permalink]
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Originally posted by H. Humbert
Now, a satellite in orbit essentially free falls around the Earth. Replace the satellite with a magnet and build a massive tube of coiled wire around its path: Bingo! Unlimited energy.
Certainly there's no reason why this set up wouldn't work, right?
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Well, I would disagree with you.
The Earth's mass is bending space-time around the planet, so when the satellite is orbiting around the Earth, it's not actually falling towards Earth but flying in a straight line. It just so happens that Earth's mass is bending that straight line into a circle (or ellips, depending on the trajectory).
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Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
Dr. Mabuse whisper.mp3
"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse
Support American Troops in Iraq:
Send them unarmed civilians for target practice..
Collateralmurder. |
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CarlaNahas
Spammer
Armenia
1 Post |
Posted - 05/09/2012 : 21:35:55 [Permalink]
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would you want one ?
low carborn
Spam links have been deleted.
Kil
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LED LIGHTS |
| Edited by - CarlaNahas on 05/09/2012 21:36:45 |
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sailingsoul
SFN Addict
2830 Posts |
Posted - 05/11/2012 : 06:36:20 [Permalink]
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| We never know where the next discovery is going to come from. If your looking for free energy look toward than the Sun. Which I believe is the largest source most readily available. It can be used to produce electricity directly and is the source of all wind , wave, hydro, solar thermal and tidal energies. It is also the source of the most energy on the planet used by living life forms, plants, animals and their parasites. Almost all life on earth runs on it with the exception of deep microbial life residing deep under ground in darkness, life living around geothermal vents which is chemical based where no light exists or our spiritual leaders and republican life forms who flourish in the darkness of intellectual ignorance and by the bigoted exploitation of the vulnerable and disenfranchised which they create and cultivate. :p |
There are only two types of religious people, the deceivers and the deceived. SS |
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 11/17/2015 : 18:15:54 [Permalink]
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I am vindicated!
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
| Edited by - H. Humbert on 11/17/2015 18:16:33 |
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sailingsoul
SFN Addict
2830 Posts |
Posted - 11/18/2015 : 22:31:40 [Permalink]
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Shell is blowing a different kind of smoke than you are, me thinks.
Not saying it doesn't work, notice how no mention is made on how often the weight needs to be raised. I had a wind up radio with a light once. At least 10 years ago. Nothing new here. Shit they just took off the radio and used a weight and pulleys instead of a spring and gears. Free energy is everywhere but people don't want to pay for it, unlike water! |
There are only two types of religious people, the deceivers and the deceived. SS |
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Would this work?
