if it is impossible to create a perpetual motion machine, why does the earth seem to run perpetually?

Answer 1

It is not impossible to invent a perpetual motion machine, it is impossible to get a patent on it.

Answer 2

It is actually slowing down. The rate of slowing is very small compared to a man made perpetual motion machine for two very simple reasons: 1) There is very little friction slowing the Earths rotation, one is the ocean tides by the way; and 2) it is really really big and heavy so there is a tremendous amount of energy stored in it's rotation.

An interesting example of a planet that has in essence stopped rotating is Mercury. Mercury does rotate but only one time as it orbits the Sun. Therefore one side of Mercury always faces the Sun - and that would be the hot side, which is really damn hot. The Moon does the same thing. One side of the Moon always faces the Earth. As a result humans had never seen the far side of the Moon until we sent spacecraft up to orbit it.

In both the case of the Moon and Mercury they are what is called "tidally locked". If a planet or the Moon were to spin so that more than one face were to point at the object it was orbiting, the forces of gravity will squeeze the planet a little bit and make the surface go up and down like a tide, even on the solid surface of the planet. That squeezing stops once the planet slows down until only one side always faces the Sun. The rotation will not stop entirely because then other parts of the planet would face the sun over the course of one orbit. Then the squeezing forces would cause it to start to spin unit it was back to just one side facing the Sun. That happened first to Mercury because it is very close to the Sun and so the tidal forces are very strong. Also it is much smaller than the Earth so it had less rotational energy to start with. The same is true of the Moon. It is pretty small and it is quite close the the Earth so tidal forces worked fast to stop it's spin.

Those are the tidal forces that are slowing down the Earth.

Answer 3

The earth orbits around the sun and does so because of gravity. In 5 billion years, when the sun starts to die out and goes through the motions of star death it will grow and gain gravitational pull. Now if the earth doesn't fall into the sun, the sun will eventually shrink into a white dwarf and no longer maintain the gravitational pull it once had. The earth will leave its orbit that it maintains and drift out into space, where over billions of years will be pounded by asteroids and other space debris and eventually crash into another planet, or star. So putting this into perspective, perpetual motion is based on motion that does not stop, but all things do come to an end.
This disproves the theory of perpetual motion, but to reiterate what was mentioned above, the earth is not a machine, therefore it does not run.

Answer 4

The earth isnt perpetual, as eventually through radioactive decay all of the radioactive elements will cease to exist. by that time, however, the sun will have imploded, destroying this tiny little rock. As to why it's impossible to create a perpetual motion machine...you would have to have energy correct? So let us say that this machine also create's it's energy, then uses it to function and create more. Theoretically the efficency would be 100%, but you're forgetting friction. static friction decreases the efficency of all machines, making 100% efficency impossible.

Answer 5

Technically a Breeder Reactor is a perpetual motion machine, it Breeds, or produces more energy than it consumes.
As for the earth, its orbit will decay and it fall into the sun in about 4 billion years.

Answer 6

The earth "seems* to run perpetually because you have a very short timeline. The existance of this planet is not perpetual and it looks like the universe might not be perpetual

Answer 7

The overbalanced wheel was solved as a model in the US several years ago and was independently verified in Australia. The drawback (and difference between it and the earth) is that a constantly overbalanced wheel accelerates at 32 fps and continues to accelerate until it reaches destructive overspeed.
The design can be seen by viewing Da Vinci's wheel and flipping the image upside down, adding outriggered counterweights and springs to mechanically make what the inverted drawing depicts.

The earth is simply turning, and will eventually slow until an external force (or newly discovered internal force) kicks up its rotational speed.

Answer 8

Due to the frictional tides from the gravitational tug of the moon, the earth's rotation is slowing down, and since momentum must be conserved, the radius of the orbit of the moon is moving about 5cm per year! One day eons from now, a "day" will be longer than 24 hours and the moon will be very far away.

The mirrors that the Apollo missions left on the moon confirm the moon is moving away!

Answer 9

The earth, when young, had a day that was ten hours or less. There are many things slowing the earth down, such as the sloshing of the oceans against the land, daily tides, the weight of the atmosphere and motion of the winds, and so on.

Answer 10

From our short time frame, it appears the earth runs perpetually, but gravity from the sun is causing the earth to slowly fall toward it (same with the moon around earth). It'll happen long after mankind has disappeared (and if we were still around, I'm sure we wouldn't be able to survive the climate change as we got closer).