Is it possible to build motor that runs on generated electricity from the motor's own kinetic energy?

Question

We just need to give it a first push and it will just run forwever and ever. Could we just put a generator and a motor together and make them both run at the same time?
Any links?

Answer 1

Yes, and it won't work.
The rotational energy from the motor would go into a reverse motor called a generator to create electricity to power the motor.

What you are talking about is the perpetual motion machine: a machine that runs forever. This one fails because of the electrical resistance in the wire, the friction in the motor and generator, air resistance (which could be removed), and the inherent inefficiency of the system. The way to generate electricity is to spin a motor. So your motor to generator idea would be easy to do, but the power generated would always be reducing until the system stopped.

Due to a nature of the universe called entropy perpetual motion is impossible. In your example the generator of the motor wouldn't be powerful enough the resistance of air and in the machine would all lose energy.

Entropy: http://en.wikipedia.org/wiki/Entropy
Sets all the things in the universe to try and approach the same temperature, a uniform distance and the same level of chaos. When that happens it will be after all the stars expire and it is an event called the heat death of the universe. The average temperature will be 4 degrees above absolute zero and falling.

All inefficiency is a product of entropy; which can be thought of as you can't get anything for free. Because of entropy; thru things like friction, resistance, heat loss, etc. you always will need to put more energy into a system to get anything out. This is why the battery can't hold a charge forever, even if it is not used and stored at a very cold temperature the chemical reaction will equalize over time discharging the battery.

The incandescent light bulb is only 40% efficient. Most of the energy is lost as heat. Light Emitting Diodes (LEDs) are 90% efficient. They generate almost no waste heat, and are so efficient that people are converting to them all over the world. All new cars use LEDs not light bulbs, traffic lights are being converted to LEDs and so on. This isn't just a cost saving measure, but it reduces the amount of electricity that needs to be generated by pollution causing systems.

Your idea isn't original; people have been searching for a perpetual motion engine for years. The best approach has been with a magnetically suspended item in a vacuum. As it spins there is almost no resistance slowing it down, but you can't have a perfect vacuum so even that resistance will eventually slow down the spinning object defeating the system.

Stars all die, planets will eventually spiral into their suns or loose their suns and float away; even black holes evaporate in Hawking Radiation. There is no perpetual motion and nothing lasts forever.

Answer 2

You might be interested in a dynamotor. That is a unit containing a motor and a generator. Many military radios from World War 2 used 12 volt power from trucks and used a dynamotor to generate 250 volts to activate the vacuum tubes. You seem to be interested in making 33,000 volts from 1000 volts at 5,000 watts. This would work, but the most current you could draw from it would be 5/33 , that is 0.151515 Amps at 33,000 volts if it were 100% efficient. As everyone else pointed out you can not get better than 100% efficiency, and in practice dynamotors were more like 30% so the maximum current you could get would be about 1/20 amp. Do not try it without professional help because 33,000 volts will jump about 2 inches through air and 1/20 amp is more than enough to kill someone.

Answer 3

No, this is called a perpetual motion device, and it is has been proven undeniably impossible (although many have tried). The motor will always slow down due to friction, because you can't have parts working together be completely frictionless. This means in order to keep it going, you need to continuously supply it with *outside* energy. The electricity might keep it going for a while, but as the friction slows it down, it generates less electricity, and eventually it would stop.

Answer 4

Unfortunately, a perpetual motion machine, such as you describe, is one of those sad impossibilities.

First and most importantly, no motor can run with 100% efficiency. The work output of a mechanical system will always be less than the energy put into it. Your engine would eventually grind to a halt.

Secondly, your engine would necessarily be useless. If all of its kinetic energy was fed right back into itself, it would have no spare energy to do anything useful.

Answer 5

That's called a perpetual motion machine. In theory - this works, unfortunately, no matter how much we try - we can't eliminate friction.

To overcome friction requires energy meaning you always have to put more into the system. Energy can not be created or destroyed - the form just changes.

In the case of friction the energy lost is turned to heat and noise. Mechanical wearing the parts, due to friction, is also an energy sink.

Answer 6

First push as off a cliff? You mean from the kinetic energy it would acquire in rolling down the hill, right? OK, I am being sarcastic. You need to get yourself a book on basic physics.

Answer 7

no that wouldn't work unless the motor is 100% efficent ie no loss, and nothing is like that, so no. it could how ever be used to partly charge a battery running it, but it wouldn't generate as much as the input im afraid

Answer 8

impossible.