Energy neither created nor destroyed

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In summary, the conversation discussed the idea of connecting a motor with a generator to create a perpetual motion machine. However, it was pointed out that this would not work due to the law of energy conservation, which states that energy cannot be created or destroyed but can only be transformed. Different power sources, such as water, fossil fuels, or wind, would be needed to generate power. The conversation also touched on personal experiences with attempting to create such a machine as a child.
  • #1
Super.man
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I am studying engineering in my preparatory year and i have an idea which i would like to know if it is true??
why don't we connect a motor with a generator ??
so if we rotated the generator with our hand , the current produced will go to the motor which will rotate due to the magnetic forces and will rotate also the generator...
so it will not stop...
but does that agree with the theory of energy :"Energy neither created nor destroyed but it can be transformed with one form to another"
 
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  • #2


Hi Super.man, welcome to PF.

Perpetual motion machines are not an accepted topic for PF. It won't work because it will take more energy to turn the motor than the generator will produce.
 
  • #3


can't i use any circuit to increase the current produced by the generator and hence increase the power .
 
  • #4


yes but then the motor will require more power...to drive a generator, you need to produce power in a way that utilizes other power sources instead of electricity...say water falling (hydroelectric power), burning fossil fuels (a diesel engine or a gas turbine) or wind...
 
  • #6


I get it now...
Thanks for explaining :cool:
 
  • #7


LOL! I remember doing this as a kid. I didn't expect it be an "eternity machine", but I did wonder if the motor would run longer by a measurable time on my clock :-)

I used a motor from a radio controlled car, and a generator from a bicycle, and connected them with a rubber belt. The amount of friction was quite high... I couldn't detect a difference, of course :-)

Really cool that this post reminded me of my scientific endeavors as a young boy.

Torquil
 

What does the law of "Energy neither created nor destroyed" mean?

The law states that energy cannot be created or destroyed, but can only be transferred or converted from one form to another. This means that the total amount of energy in a closed system remains constant.

How does this law apply to everyday life?

In everyday life, this law applies to all forms of energy, including mechanical, thermal, chemical, and electrical energy. For example, when we turn on a light bulb, electrical energy is converted into light and heat energy. When we drive a car, the chemical energy in gasoline is converted into mechanical energy for movement.

Does this law apply to the entire universe?

Yes, this law applies to the entire universe. It is a fundamental principle in physics known as the first law of thermodynamics. It applies to all systems, whether they are on a microscopic or a cosmic scale.

Can energy be created or destroyed in nuclear reactions?

In nuclear reactions, the total amount of energy before and after the reaction remains the same. However, nuclear reactions can result in the conversion of mass into energy, as shown by Einstein's famous equation E=mc^2. This means that the amount of energy in the universe can change, but it cannot be created or destroyed.

Why is the law of "Energy neither created nor destroyed" important in science?

This law is important because it helps scientists understand and predict the behavior of energy in various systems. It also allows us to develop technologies that harness and utilize energy in a sustainable manner. Without this law, the universe would be constantly changing and unpredictable, making it difficult for scientists to make accurate predictions or create reliable technologies.

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