Priority Claim

[Ed]

But then you Brits often talk funny. :)}

They get away with it because they have their tea vouching for them, don't they. :-)

[rlortie]

...can you name any form of energy that does not provide heat when utilized?

Nope.

Can you name any form of heat that is not created by some form of heat?

How about the heat of anger! what I do when Jim and or grimer have to relate/twist things with reference to space or in a orbital space station. We are looking for and talking about earthbound directives. I could care less about what will or will not work in space.

More than once, jim_mich has responded (twisted) my input by responding with what would happen in a non-gravitational field aka space.

Let's keep it on the ground guy's, and then I will not produce so much heat!

Ralph

[justsomeone]

Actually Ralph taking gravity out of the equation is a reasonable line of questioning.

[rlortie]

jso,

I agree that "taking gravity out of the equation is a reasonable line of questioning". Providing you are on the topic of orbital objects and or in a non-gravitation field.

When us poorly earthbound members ask a earthbound question, I do not seek nor expect an answer related to what happens in space!

IMO, space talk should be limited to "Off Topic"

[Andyb]

Implosive gases they seem just as elusive as pm but endothermic gases do exist .

[rlortie]

Andyb,

When you speak of implosive gases, are you referring to natural gas or something like Browns gas?

http://amasci.com/weird/bgf1.html

Ralph

[Grimer]

jso,

I agree that "taking gravity out of the equation is a reasonable line of questioning". Providing you are on the topic of orbital objects and or in a non-gravitation field.

When us poorly earthbound members ask a earthbound question, I do not seek nor expect an answer related to what happens in space!

IMO, space talk should be limited to "Off Topic"

In deference to your wish to remain earthbound I have removed my Mr Spock avatar. ;-)

[Grimer]

...
The only way angular momentum can be added to the system is to create a mechanical connection to the exterior inertial (non rotating) reference frame and then use this connection to "pump" the system using internal muscle energy (as in Frank's example).

This raises the most interesting question as to what is the system and what is "outside" the system.

If we look at the thing hierarchically then we can have energy which is outside the system while, paradoxically, being inside the system.

Think of a block of flats. The people on the 21st floor are outsiders to the people on the 20th floor but the people on the 19th floor are also "outsiders".

Of take these Russian style dolls:



For number two with the arrow, number 1 is outside both in physical and system terms. Numbers 3, 4, 5 and 6 are inside physically but outside systemwise (think of number 6 as zeropoint energy :-) ).

So everything depends on where we define the hierarchical boundaries of our "system".

Ultimately the whole thing becomes a tautology. Energy is conserved because we close the system from energy coming from without (the ceiling) and energy coming from within (the floor).

But if we open the ceiling or the floor then energy is no longer conserved.

The GPM depends on opening and closing the system.

When the Simple Pendulum (SP) starts to fall the Earth (E) reaction on the Compound Pendulum (CP) starts up and the Earth becomes part of the system.

The Newtonian gravitational energy of the simple pendulum is then outside the CP/E system and is going to be fed into that system from the outside.

Then the SP hits the spring, disconnects the Earth and we now have a new system, the CP into which the SP feeds part of its energy.

The SP then recoils and forms the original balanced beam system before the CP has time to use up its energy in overcoming its small net Newtonian gravitational reaction.(cf the High Road/Low Road demonstration).

The now balanced beam system rotates with the remaining energy of the compound pendulum. This "flywheel" rotation can be bled off as gravitational energy while the balanced beam is slowing down to its reset position.

Jim complains that the GPM seems too simple.

It is indeed simple - but only if you understand what you are doing.

[cloud camper]

That is fascinating Frank.

In your rotating space station example (sorry Ralph) one can use muscle
energy to keep raising weights off the floor up to a shelf.

We continue to perform actual work to raise the GPE of weights relative to the floor. We are doing physical work against the fictitious force CF.

Now we stop the rotation of the space station. We never added any angular momentum to the station but now all the internal GPE we added thru biological work is "lost".

It simply disappears because the reference frame it was based on no longer exists.

Where did all this added GPE go? We did actual work against a fictitious force so the GPE we added was fictitious too!

This would seem to be a case of actual energy destruction as the biological energy used to raise weights inside the rotating station is completely lost as it was never converted to any other form of energy.

Now if we could just reverse the situation!

[rlortie]

CC,

Is this any different than lifting a weight earthbound creating your GPE or simply Pe and then dropping it, is not all the biological energy lost?

It disappears as the reference frame (height you lifted the weight) no longer exists, If the weight lands in the same place you picked it up, no work has been accomplished.

Difference between space station and earth is 'fictional force verses conservative force. What happened to the physical force you ask, iMO you used it to lift the weight which is considered work.

If gravity moves it back from your point of reference is it not also doing work?

Brevity clip from Wiki;

In physics, a force is said to do work when it acts on a body, and there is a displacement of the point of application in the direction of the force. For example, when you lift a suitcase from the floor, the work done on the suitcase is the force it takes to lift it (its weight) times the height that it is lifted.

The term work was introduced in 1826 by the French mathematician Gaspard-Gustave Coriolis[1][2] as "weight lifted through a height", which is based on the use of early steam engines to lift buckets of water out of flooded ore mines. The SI unit of work is the newton-metre or joule (J).

The work done by a constant force of magnitude F on a point that moves a displacement (not distance) s in the direction of the force is the product,

Ralph

[rlortie]

Lets take a closer look at the last sentence in my above Wiki quote;

The work done by a constant force of magnitude F on a point that moves a displacement (not distance) s in the direction of the force is the product,

In the case of liquid seeking its on level, I would think that the displacement is not in the direction of the force but at a right angle, any thoughts on this would be appreciated.

Ralph

[Dunesbury]

Are you on earth or in spaceship?
lol
So sorry, I couldn't resist!

[cloud camper]

CC,

Is this any different than lifting a weight earthbound creating your GPE or simply Pe and then dropping it, is not all the biological energy lost?

It disappears as the reference frame (height you lifted the weight) no longer exists, If the weight lands in the same place you picked it up, no work has been accomplished.

Difference between space station and earth is 'fictional force verses conservative force. What happened to the physical force you ask, iMO you used it to lift the weight which is considered work.

If gravity moves it back from your point of reference is it not also doing work?

Brevity clip from Wiki;

In physics, a force is said to do work when it acts on a body, and there is a displacement of the point of application in the direction of the force. For example, when you lift a suitcase from the floor, the work done on the suitcase is the force it takes to lift it (its weight) times the height that it is lifted.

The term work was introduced in 1826 by the French mathematician Gaspard-Gustave Coriolis[1][2] as "weight lifted through a height", which is based on the use of early steam engines to lift buckets of water out of flooded ore mines. The SI unit of work is the newton-metre or joule (J).

The work done by a constant force of magnitude F on a point that moves a displacement (not distance) s in the direction of the force is the product,

Ralph

Ralph - the reference frame in your example is an inertial frame that does not disappear when you drop the weight. The inertial frame here is the surface of the earth. This is unlike the non-inertial (rotating) frame of the space station which disappears when the station stops rotating.

In your example the energy you used to raise the weight creates a greater GPE that is then recoverable if you used that height to operate a lever or drive a pump.

If you just drop the weight, the energy is dissipated as heat when the weight impacts the ground. Not too useful, but the energy is converted and conserved. The inertial reference frame is still there.

In the rotating non-inertial frame, the internal GPE created by raising weights within the frame is real, but only as long as the station is rotating. When the station stops rotating, all internal GPE is lost as the reference frame does not exist anymore.

[Dunesbury]

Can system of weights be connected to inside of space station in some way to cause station to rotate from rest and do work on another station?

[ovyyus]

Now we stop the rotation of the space station. We never added any angular momentum to the station but now all the internal GPE we added thru biological work is "lost".

Really? Lifting a weight against CF (earthbound eg: spinning ice skater pulls arms inwards) would cause the space station to increase angular momentum. The increase is proportional to the work done. Therefore, no energy is "lost".