bascule Posted February 7, 2008 Posted February 7, 2008 An inventor has constructed a perpetual motion machine. The device, which he has dubbed the Perepiteia, runs on an endless supply of media stupidity: http://www.thestar.com/Business/article/300042?746
Klaynos Posted February 7, 2008 Posted February 7, 2008 This reminds me... http://blogs.scienceforums.net/swansont/archives/20
Realitycheck Posted February 7, 2008 Posted February 7, 2008 Prove me wrong, but it seems to me that if you have a motor-like contraption where the spindle is magnetic and the outer brushes are magnetic, then you should be able to arrange things to harness force out of the repulsion between the two magnets and make it spin. I'm sure I am probably missing something but it sounds doable. Wait a minute. That's kind of what it says down at the bottom. Wouldn't someone have thought of this by now? I mean, electric motors have been around for a while.
Klaynos Posted February 7, 2008 Posted February 7, 2008 Prove me wrong, but it seems to me that if you have a motor-like contraption where the spindle is magnetic and the outer brushes are magnetic, then you should be able to arrange things to harness force out of the repulsion between the two magnets and make it spin. I'm sure I am probably missing something but it sounds doable. Wait a minute. That's kind of what it says down at the bottom. Wouldn't someone have thought of this by now? I mean, electric motors have been around for a while. You're forgetting friction, it'll slow down and end up in a stationary equilibrium point in the lowest energy state.
Daecon Posted February 7, 2008 Posted February 7, 2008 What if the magnet is suspended in mid-air by repulsive magnetic forces?
Klaynos Posted February 7, 2008 Posted February 7, 2008 What if the magnet is suspended in mid-air by repulsive magnetic forces? Still friction... What about a vacuum... Perfect vacuums don't exist, still friction...
swansont Posted February 7, 2008 Posted February 7, 2008 This reminds me... http://blogs.scienceforums.net/swansont/archives/20 Yep. Gotta wonder why nobody has bothered to plug it in to itself and remove the wall plug, and report on what happens. Prove me wrong, but it seems to me that if you have a motor-like contraption where the spindle is magnetic and the outer brushes are magnetic, then you should be able to arrange things to harness force out of the repulsion between the two magnets and make it spin. I'm sure I am probably missing something but it sounds doable. Wait a minute. That's kind of what it says down at the bottom. Wouldn't someone have thought of this by now? I mean, electric motors have been around for a while. It still draws power to do that.
Klaynos Posted February 8, 2008 Posted February 8, 2008 Yep. Gotta wonder why nobody has bothered to plug it in to itself and remove the wall plug, and report on what happens. Because they all know it'd FAIL!!!
DrP Posted February 8, 2008 Posted February 8, 2008 you guys have probably seen this before but my avitar is an example of a fully working PM machine! Just look -- the 9's are heavier than the 6's so the wheel will roll to the right continually!
iNow Posted February 8, 2008 Posted February 8, 2008 you guys have probably seen this before but my avitar is an example of a fully working PM machine! Just look -- I thought your avatar existed?
Reaper Posted February 8, 2008 Posted February 8, 2008 Note that the article begins with the words "college dropout".
insane_alien Posted February 8, 2008 Posted February 8, 2008 because they think magnets are some magical thing only vaguely understood by scientists.
swansont Posted February 8, 2008 Posted February 8, 2008 Why is it always magnets with these guys? If only. Hydrinos, zero-point, cold fusion, overbalanced wheels, antigravity. The woo spreads far, wide and deep.
doG Posted February 8, 2008 Posted February 8, 2008 Isn't all motion perpetual according to Newton's first law of motion?
Mr Skeptic Posted February 8, 2008 Posted February 8, 2008 Isn't all motion perpetual according to Newton's first law of motion? In this house we obey the laws of thermodynamics! Don't forget the second law of thermodynamics, which says entropy always increases. Newton's first law only applies if there is no force on the object, though that is often a pretty good approximation of a near frictionless environment. He had to state it like that because before that people thought things always decelerated if you stopped pushing them. Basically, things keep moving at a constant velocity unless acted upon by a force, and a friction force of some kind or other is always present to some extent.
Daecon Posted February 8, 2008 Posted February 8, 2008 I think doG was referring to every action causing an equal and opposite reaction...?
swansont Posted February 8, 2008 Posted February 8, 2008 I think doG was referring to every action causing an equal and opposite reaction...? That would be the third law. Perpetual motion is not really addressed by Newton's first law. As Mr Skeptic points out, that law merely tells you that motion will be uniform if there is no force, but there is nothing that assures us that this will be the case.
doG Posted February 8, 2008 Posted February 8, 2008 I think doG was referring to every action causing an equal and opposite reaction...? No, I was referring to Newton's First Law, "Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it." This implies if there are no external forces like friction or gravity acting on a body in motion then a body in motion tends to remain in motion. Think of planets in motion, etc. in the vacuum of space or the orbits of electrons about their nucleus in the atom. Motion is perpetual by definition. What is not possible is deriving energy from such motion which would effectively apply an external force. In this case the first law of thermodynamics would apply as well, i.e. "for a thermodynamic cycle the sum of net heat supplied to the system and the net work done by the system is equal to zero." IOW, you only get out what you put in....
Sisyphus Posted February 8, 2008 Posted February 8, 2008 "Perpetual motion" usually means getting more work out of a system than you put in. Newton's first law just says that if the system isn't doing any work, it will continue in motion indefinitely. This doesn't actually happen in our universe (stupid entropy), but it could. Sort of. "Perpetual motion" taken literally is the limiting case, which can be approached indefinitely close but not reached. "Perpetual motion" in the usual sense is impossible for more reasons, such as that pesky conservation stuff.
Klaynos Posted February 9, 2008 Posted February 9, 2008 No, I was referring to Newton's First Law, "Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it." Name a situation where there is no external froces? This implies if there are no external forces like friction or gravity acting on a body in motion then a body in motion tends to remain in motion. Think of planets in motion The planets orbits are changing all the time, slowing down and falling into the sun. , etc. in the vacuum of space Is not a perfect vacuum at all. or the orbits of electrons about their nucleus in the atom. Are not orbits, and even if they where the electrons would be radiating energy (as accelerating charges do, as shown by the Maxwell equations) and they would shoot into the nucleus in a few orbits. Motion is perpetual by definition. What is not possible is deriving energy from such motion which would effectively apply an external force. In this case the first law of thermodynamics would apply as well, i.e. "for a thermodynamic cycle the sum of net heat supplied to the system and the net work done by the system is equal to zero." IOW, you only get out what you put in.... Infact you only get out less than you put in... ALWAYS... As the Carnot cycle will show.
ydoaPs Posted February 9, 2008 Posted February 9, 2008 Isn't all motion perpetual according to Newton's first law of motion? Only in situations where there is a zero net force on the system in motion. Such situations do not exist(there will always be friction, I2R losses, etc). Don't forget the second law of thermodynamics, which says entropy always increases. NO. That is NOT what it says(sorry, pet peeve of mine). If entropy always increased, I'd be out of a job. Newton's first law only applies if there is no force on the object, though that is often a pretty good approximation of a near frictionless environment.Again, you're not correct. Newton's first law ALWAYS applies in inertial reference frames. If there is zero NET force on an object, the velocity will remain unchanged. Basically, things keep moving at a constant velocity unless acted upon by a force, and a friction force of some kind or other is always present to some extent.Things keep moving unless acted upon by an external non-zero net force.
doG Posted February 9, 2008 Posted February 9, 2008 Name a situation where there is no external froces? I can't think of any. Does that mean Newton's law is invalid? His law effectively says that motion is perpetual unless something stops it. Are you claiming this law is false?
Klaynos Posted February 9, 2008 Posted February 9, 2008 I can't think of any. Does that mean Newton's law is invalid? His law effectively says that motion is perpetual unless something stops it. Are you claiming this law is false? No, I'm claiming your interpretation of his law is flawed and incorrect.
YT2095 Posted February 9, 2008 Posted February 9, 2008 all these PM machines make me giggle, there`s no way Any of them can work! take a look at the Real Thing here: http://uk.youtube.com/watch?v=jYcjjSfiNNE you KNOW it makes sense! now keep repeating "there is no Second Law... there is no Second Law..."
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