Can a perpetual motion machine truly exist?

[fooktade]

in one of the laws o physics it says in laymans terms you can't get more energy out of something then you put in. what if you by putting energy into a source caused it to get more energy from other sources? would this prove to create a infinite amount of energy?

 

[Fewmet]

in one of the laws o physics it says in laymans terms you can't get more energy out of something then you put in. what if you by putting energy into a source caused it to get more energy from other sources? would this prove to create a infinite amount of energy?

Welcome to Physics Forums, fooktade.

You are referring to the law of conservation of energy. One statement of it is that the total energy in a closed system is constant. (Another equivalent statement says that energy is neither created nor destroyed in a closed system.) You can think of "closed system" as meaning that no energy is added or removed by outside agents.

I think what you are suggesting is, say, having a battery powered motor also draw on solar panels (the "other sources"). In this case the closed system is the motor, battery, solar cells and the sun. The total energy that the engine can produce is still limited to the energy that is in the system at the start.

 

[DaveC426913]

in one of the laws o physics it says in laymans terms you can't get more energy out of something then you put in. what if you by putting energy into a source caused it to get more energy from other sources? would this prove to create a infinite amount of energy?

If you device is, as you say "pulling energy from other sources" then it's ... well .. pulling energy from other sources, isn't it? So why would that create any energy, let alone an infinite amount?


You're got a little fan attached to a battery. Fan starts up, and at a certain speed, it flips a switch, closing a circuit to a second battery and a little solar panel.

OK so now you device is powered by two batteries and a solar panel (which means your household AC is powering it by way of a lightbulb).

None of this is unexpected.

 

[fooktade]

well what if you had a battery move a object and while its moving a wind turbine produces energy along with the generators on the axle that would move the object. would this works?

 

[fooktade]

Fewmet- not quite what i was getting

 

[Ryan_m_b]

well what if you had a battery move a object and while its moving a wind turbine produces energy along with the generators on the axle that would move the object. would this works?

Work at what? A wind turbine charges a battery that drives a motor is a perfectly workable idea. It's not infinite energy though, you are taking energy from one source (the wind) and transferring it elsewhere.

 

[fooktade]

yes but you would also have the turbines on the axles to create energy and solar panels. this way you have 3 sources of energy

 

[Ryan_m_b]

yes but you would also have the turbines on the axles to create energy and solar panels. this way you have 3 sources of energy

It doesn't matter how many sources of energy you have, none are infinite.

 

[fooktade]

yes true but would it be able to create more energy then it uses

 

[Ryan_m_b]

I think you have a bit of a misunderstanding here, it's a fundamental phenomenon in this universe that a little bit of energy can be used to create a chain reaction releasing more energy. Think of a litre of oil, it takes a little energy (i.e. a spark) to release the energy of the oil.

Using less energy than is made is ubiquitous, using no energy to make energy is impossible, lastly there can be no infinite energy systems thanks to entropy

 

[fooktade]

i understand that and you answered my question "with I think you have a bit of a misunderstanding here, it's a fundamental phenomenon in this universe that a little bit of energy can be used to create a chain reaction releasing more energy. Think of a litre of oil, it takes a little energy (i.e. a spark) to release the energy of the oil."
i just wasn't sure about something

 

[Ryan_m_b]

You might be interested in looking up entropy, it's the reason why perpetual motion and infinite energy do not exist.

 

[fooktade]

ok. i just need some help designing stuff to test out this thing I am making

 

[Ryan_m_b]

ok. i just need some help designing stuff to test out this thing I am making

Thing?

 

[fooktade]

i was working on a car that powers itself. i had some ideas and i wanted to test them out

 

[Ryan_m_b]

i was working on a car that powers itself. i had some ideas and i wanted to test them out

I fear I should warn you now that perpetual motion has a long history of failure.

 

[fooktade]

lol yes but i thought this would be worth a try. i just need to test a couple things but i don't quite know how.

 

[fooktade]

i can't find out how to find the drag of a object or how much energy would be needed sense it would not use a normal motor

 

[fooktade]

you seem to know a lot more about this stuff then me. i have only read through a couple basic textbooks so if you wouldn't mind can you help me a little

 

[DaveC426913]

you seem to know a lot more about this stuff then me. i have only read through a couple basic textbooks so if you wouldn't mind can you help me a little

We're definitely trying to help you.

You're going to build a vehicle that's powered by a source of energy, then you're going to attach a generator to the axles, or put turbines on it to try to extract energy from the wind, or some other such secondary device to try to extract energy.

It will not work. Here's why:

Attaching any device to extract energy (such as a generator on the axle or turbines in the wind) will increase the work your primary motor needs to do to move the vehicle. Any gains you make from these secondary devices will be stolen directly from the extra work your primary motor needs to do in the first place.

eg. your gas-powered car gets 20mpg. Add a turbine to extract energy. The amount of energy the trubine extracts is directly proportional to how much harder the engine will have to work. Now, you can supplement the motor with electicity, except that your gas engine now only gets 10mpg.


Further, making the system more complex means more moving parts, more friction and more energy lost to heat. To make the most efficient use of energy, you want to minimize wasteful complexity, not make it worse.

 

[fooktade]

i see what you are saying but i was thinking of using a different type of propulsion system that quite different then a normal motor. using a electromagnetic propulsion system i feel it would be able to have a lost less drag then a normal car while creating more energy through these means

 

[Ryan_m_b]

What do you mean by creating more energy? Energy cannot be created or destroyed.

 

[DaveC426913]

i see what you are saying but i was thinking of using a different type of propulsion system that quite different then a normal motor. using a electromagnetic propulsion system i feel it would be able to have a lost less drag then a normal car while creating more energy through these means

The principle is no different - it doesn't matter what your primary engine is. Whatever mechanism you use to power your vehicle, it will have to work harder when you introduce some secondary mechanism that extracts usable work from it.

And if you can get more work out of your primary system, then you don't need the secondary.

 

[Naty1]

fook: You should read about the big bang..."something from nothing" apparently!

But not currently useful in THIS world.

 

[Lost in Space]

Is dark energy increasing proportionally to the size of the universe or is it fixed? Doesn't the increase in the volume of space point to some kind of energy input?

 

[DaveC426913]

Is dark energy increasing proportionally to the size of the universe or is it fixed? Doesn't the increase in the volume of space point to some kind of energy input?

New topic = new thread. Please.

 

[scupydog]

Hi https://www.physicsforums.com/member.php?u=332254

The reason i joined PF 5 years ago was with a similar question i had after finding this site http://www.besslerwheel.com/

This site concerns a perpetual motion machine.

But after talking to the people on PF i now realize that there can be no such machine.

I took me about 1 year to get the idea out of my head.

When you learn why no such thing can exist, will be 1 stage nearer to being the ultimate physicist.

Good luck with your endeavour but the sooner you understand the sooner you can move on.

Regards Dave...