A perpetuum mobile is defined as a machine that is providing mecanical energy whithout an external energy suply.
2007-10-26 21:58:08 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Physics
The three laws of thermodynamics, slightly restated:
1) You can't win. (You can't get something for nothing).
2) You can't break even.
3) You can't quit the game.
All "perpetual motion" schemes involve trying to ignore one or more of these laws. For instance, many schemes assume that you can actually make a frictionless axle (which violates the second law - entropy always increases).
2007-10-26 22:10:01 · answer #1 · answered by Valdis K 6 · 0⤊ 1⤋
The most intuitive answer is simply that friction cannot be overcome outside of a perfect vacuum. So there will always be a drag against whatever motion is occurring.
With a pendulum type device, there is friction in the suspension cable. With an electro-magnetic device, there is resistance in the wiring (actually friction of the electrons within the metal wire). With a spinning type device, there is friction at the contact point(s) between the axis and the supporting platform.
Ultimately, without additional energy of some sort, whatever it is will eventually stop.
That being said, as a physics student, attempting to create perpetual motion can be one of the most educational activities available, akin to “squaring the circle” in mathematics.
2007-10-27 07:35:30 · answer #2 · answered by web-eagle 3 · 0⤊ 0⤋
There will always be some external energy source involved, like gravity.
2007-10-26 22:02:11 · answer #3 · answered by Anonymous · 0⤊ 0⤋
No, the second law of thermodynamics prohibits such a machine
2007-10-26 22:20:05 · answer #4 · answered by maussy 7 · 0⤊ 1⤋
erw
2016-09-16 02:07:25 · answer #5 · answered by john 1 · 0⤊ 0⤋