This is just a straight cross-post of a thread on the old board, from 2011 :
https://www.tapatalk.com/groups/the_coff...f=7&t=1632
I'm sure we've all heard of these. The idea of a perpetual motion machine is that, once you set it going, it can continue forever, without any outside source of energy (such as fuel). Sometimes, they are intended to produce more energy than they require to operate, so that this 'free energy' can then be used to perform useful work.
It sounds like we could use one right about now, to solve all the world's energy problems. Unfortunately, according to our current understanding of physics, they would be impossible, because such a machine would violate the First Law of Thermodynamics (which essentially states that in a closed system, the total energy remains constant). Many would also run into trouble with the Second Law of Thermodynamics (i.e. in a closed system, the net entropy must increase). It should be noted that saying that anything is completely impossible is unscientific: if, hypothetically, someone were to build a true perpetual motion machine, then it would just mean that the laws of thermodynamics were falsified. Let's face it, though: the laws of thermodynamics are so well founded that that just isn't going to happen in reality.
However, perpetual motion machines do have one perpetual quality: people perpetually invent them . Unfortunately, nobody's built one that works yet: either they stop eventually, or they rely on some external energy source (and thus are not true 'perpetual motion machines'). Here are just a few:
(Click to enlarge; Source: Citron; shared under CC BY-SA 3.0 licence)
A lot of early ones (like these ones, designed by Leonardo da Vinci) were based on wheels. The basic idea was that the wheel contained a series of masses, which were free to move in some way. Those towards the top of the wheel would fall in towards the centre, and those towards the bottom would fall out away from the centre, and the resulting difference in torque would be able to keep the thing going forever. There were about a million different variants on this basic theme, none of which worked.
This one was designed in the 17th Century by the Bishop of Chester, Bishop Wilkins. The idea was that there was a ramp with a big magnet at the top, and a small magnetic ball was placed on the ramp. The magnet would attract the ball up the ramp, but before reaching the top, the ball would fall through a hole, which would take it to the bottom of a ramp. The above video shows the principle in action (although a lot of people are disputing its authenticity in the comments section; some are suggesting, for example, that the camera is attached to the table, and the whole table is being tilted back and forth to create the illusion. The main problem with this design is, any magnet powerful enough to pull the ball up the ramp would also pull it over the hole!)
(Click to enlarge; Public domain)
This is a diagram of a machine built and exhibited by American inventor Charles Redheffer in the early 19th Century. As with many other perpetual motion machines that were put on public exhibition, this turned out to be a con: it was eventually discovered that there was an old man in the attic operating it constantly with a crank.
(Click to enlarge; Source: Wellcome Collection; Shared under CC BY 4.0 licence)
Cox's Timepiece, which operates on changes in atmospheric pressure. It's sometimes thought of as a perpetual motion machine, but technically, it isn't, as it does use an outside energy source (albeit not one that is readily apparent).
So, do you have any favourite perpetual motion machines that you would like to discuss?
https://www.tapatalk.com/groups/the_coff...f=7&t=1632
I'm sure we've all heard of these. The idea of a perpetual motion machine is that, once you set it going, it can continue forever, without any outside source of energy (such as fuel). Sometimes, they are intended to produce more energy than they require to operate, so that this 'free energy' can then be used to perform useful work.
It sounds like we could use one right about now, to solve all the world's energy problems. Unfortunately, according to our current understanding of physics, they would be impossible, because such a machine would violate the First Law of Thermodynamics (which essentially states that in a closed system, the total energy remains constant). Many would also run into trouble with the Second Law of Thermodynamics (i.e. in a closed system, the net entropy must increase). It should be noted that saying that anything is completely impossible is unscientific: if, hypothetically, someone were to build a true perpetual motion machine, then it would just mean that the laws of thermodynamics were falsified. Let's face it, though: the laws of thermodynamics are so well founded that that just isn't going to happen in reality.
However, perpetual motion machines do have one perpetual quality: people perpetually invent them . Unfortunately, nobody's built one that works yet: either they stop eventually, or they rely on some external energy source (and thus are not true 'perpetual motion machines'). Here are just a few:
(Click to enlarge; Source: Citron; shared under CC BY-SA 3.0 licence)
A lot of early ones (like these ones, designed by Leonardo da Vinci) were based on wheels. The basic idea was that the wheel contained a series of masses, which were free to move in some way. Those towards the top of the wheel would fall in towards the centre, and those towards the bottom would fall out away from the centre, and the resulting difference in torque would be able to keep the thing going forever. There were about a million different variants on this basic theme, none of which worked.
This one was designed in the 17th Century by the Bishop of Chester, Bishop Wilkins. The idea was that there was a ramp with a big magnet at the top, and a small magnetic ball was placed on the ramp. The magnet would attract the ball up the ramp, but before reaching the top, the ball would fall through a hole, which would take it to the bottom of a ramp. The above video shows the principle in action (although a lot of people are disputing its authenticity in the comments section; some are suggesting, for example, that the camera is attached to the table, and the whole table is being tilted back and forth to create the illusion. The main problem with this design is, any magnet powerful enough to pull the ball up the ramp would also pull it over the hole!)
(Click to enlarge; Public domain)
This is a diagram of a machine built and exhibited by American inventor Charles Redheffer in the early 19th Century. As with many other perpetual motion machines that were put on public exhibition, this turned out to be a con: it was eventually discovered that there was an old man in the attic operating it constantly with a crank.
(Click to enlarge; Source: Wellcome Collection; Shared under CC BY 4.0 licence)
Cox's Timepiece, which operates on changes in atmospheric pressure. It's sometimes thought of as a perpetual motion machine, but technically, it isn't, as it does use an outside energy source (albeit not one that is readily apparent).
So, do you have any favourite perpetual motion machines that you would like to discuss?
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