A Fun Thing

[2012]

So I came up with this at work.

Who wants to explain why it can't work?

 

 

[iNow]

Friction.

There's also entropy.

 

Next?

[antimatter]

Friction.

There's also entropy.

 

Next?

 

 

 

Ah iNow got here ahead of me...in the case of friction, that is.

I didn't really think that entropy mattered all that much,

can you explain why entropy would work against perpetual motion? I don't think that I understand what you're trying to say...

[ecoli]

Ah iNow got here ahead of me...in the case of friction, that is.

I didn't really think that entropy mattered all that much,

can you explain why entropy would work against perpetual motion? I don't think that I understand what you're trying to say...

 

a perpetual motion device is an ordered system, but in order to prevent entropy (increase of disorder), you need to add energy, which violates the notion of a perpetual motion device.

[Gilded]

Ah iNow got here ahead of me...in the case of friction, that is.

I didn't really think that entropy mattered all that much,

can you explain why entropy would work against perpetual motion? I don't think that I understand what you're trying to say...

 

Perpetual motion relies on 100% energy conservation, which isn't possible if there is any friction. As more and more energy becomes unavailable the motion will gradually slow down. In this case, some of the mechanical work is converted into thermal energy due to friction. In this process, available energy for mechanical work is lost (entropy increases), as it is impossible to convert thermal energy to mechanical work in a 1:1 ratio as described by the second law of thermodynamics.

[2012]

That's a great regurgitation of theory but what's wrong with the design?

You can't say that it's wrong because Newton was right because if it's right then Newton was wrong, right?

[iNow]

The design is all well and good, but it will still require energy input. As ecoli mentioned, it's a system and will become more disordered as time passes.

 

http://en.wikipedia.org/wiki/Second_law_of_thermodynamics

 

 

Oh yeah, and friction.

[Cap'n Refsmmat]

The design might work if there were no friction at all. The trouble is that you will gradually lose energy to friction in the bearings and such.

[iNow]

http://en.wikipedia.org/wiki/Friction

 

http://en.wikipedia.org/wiki/Perpetual_motion

[2012]

This has nothing to do with conserving energy or ignoring friction. This design is based on torque. The fact that gravity and matter exist completely contradicts the second law of thermodynamics.

 

Here's the type of perpetual motion machine that relies on there being no friction. They're different.

 

[iNow]

Which part of any of the links I shared do you think are wrong?

[2012]

Oh none of the information shared by the links is wrong.

But those principals have to be taken in context.

 

I thought you physicists would enjoy examining this sort of thing and stretching your brains a little. I'm convinced that no one has looked at this beyond the title. You say it's wrong because you believe it's wrong and that's the only reason you give.

 

Friction is not an issue with this design. It will either move and work as a perpetual motion device or it wont move at all.

Maybe I should post it on 4chan, they might get a kick out if it.

[padren]

So I came up with this at work.

Who wants to explain why it can't work?

 

Lets say the small wheel's weight starts to drop, picking up speed, passes the point of equilibrium, and starts to slow down until the formerly-larger-now-smaller wheel's capacity to over power it stops it all together, and takes over in the reverse direction.

 

Due to friction, the weight will not get all the way down to its fullest potential, lets say, it makes it 99% of the way there because its very very efficient. The other weight is now 99% of the full height that the initial one was, and it will only drop 99% of that value - roughly 98% of the total possible distance. This will continue until the machine comes to rest in the dead center - at equilibrium.

 

What I think you failed to consider, is that speed is only being gained during the first half of the free-fall while one wheel is smaller than the other - as soon as they pass equal size at the half way point and it gradually slows.

 

It needs every last possible iota of energy to get the other end back up to it's original position - making harvesting energy impossible and friction it's "slow death" into equilibrium.

 

It is a clever adaption of the pendulum though - just less efficient and, still not a perpetual motion machine.

[Gilded]

Friction is not an issue with this design. It will either move and work as a perpetual motion device or it wont move at all.

 

There will be friction, thus there will be conversion of mechanical work into thermal energy. That seems like an issue to me.

[2012]

Lets say the small wheel's weight starts to drop, picking up speed, passes the point of equilibrium, and starts to slow down until the formerly-larger-now-smaller wheel's capacity to over power it stops it all together, and takes over in the reverse direction.

 

Due to friction, the weight will not get all the way down to its fullest potential, lets say, it makes it 99% of the way there because its very very efficient. The other weight is now 99% of the full height that the initial one was, and it will only drop 99% of that value - roughly 98% of the total possible distance. This will continue until the machine comes to rest in the dead center - at equilibrium.

 

What I think you failed to consider, is that speed is only being gained during the first half of the free-fall while one wheel is smaller than the other - as soon as they pass equal size at the half way point and it gradually slows.

 

It needs every last possible iota of energy to get the other end back up to it's original position - making harvesting energy impossible and friction it's "slow death" into equilibrium.

 

It is a clever adaption of the pendulum though - just less efficient and, still not a perpetual motion machine.

 

The weight of each weight remains constant regardless of the length of the cord. It's not a pendulum. It's not a seesaw. One side has more torque than the other and so one side will continually decend until it has gone down all the way. Gravity is a constant. Then the switch occurs and the process reverses. No weight needs to be lifted when the switch occurs.

[Cap'n Refsmmat]

Okay, I'm going to try to follow your diagrams exactly here.

 

Let's suppose we build your device so that the large wheel will have a circumference of 8cm and the small a circumference of 4cm. The inner peg that the weights are wound around have a circumference of 2cm. The string the weights hang from is 40cm long, so it's wound around the inner peg 20 times.

 

So, we start the device up. The weight is hanging 40cm down from the large pulley (pulley A) and is 0cm down from the small, ready to fall. It falls all the way down, making the small pulley (pulley B) revolve 20 times. This makes the large pulley revolve 10 times (2:1 ratio), bringing the second weight only up 20cm.

 

Current status: pulley A has a weight hanging 20cm down, pulley B one hanging 40cm down.

 

Switch occurs. Pulley A is now small and pulley B large.

 

The weight falls the rest of the 20cm from pulley A, making it revolve 10 times. This makes pulley B revolve 5 times, bringing its weight up only 10cm.

 

You're left with one weight 40cm down and one 30cm down.

 

It'll continue to diminish until it stops.

[DrP]

I'm sure you've seen this, it's silly, but I think it's cute.

 

As they pass the apex, the 6's become 9's and thus drag the wheel down on the right hand side - propelling the wheel to the left.

 

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[Phi for All]

Friction is not an issue with this design. It will either move and work as a perpetual motion device or it wont move at all.

Maybe I should post it on 4chan, they might get a kick out if it.

Maybe you should build it.

[antimatter]

Maybe you should build it.

 

Good idea Phi!

Build it, and then get back to us on the results.