eat_a_bin
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I have a question, does taking a block of ice up the stairs increase its internal energy
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Moonbow
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ummm, well your chemical energy store is being transferred to kinetic energy and you lift it, so work is done on the ice but that would be a very small change and the natural heat of your hand increases the internal energy.
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Moonbow
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so yes?? XD
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eat_a_bin
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(Original post by Moonbow)
so yes?? XD
thnx
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NonIndigenous
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Not really.

Potential energy, yes. Internal, no.
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Meowstic
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It depends on what you are doing. In most cases you'd say no, it increases the energy stored in the gravitational field; but it can be convention in thermodynamics to include all energies capable of doing work in the internal energy, so if you were doing a thermodynamical calculation then maybe but with most definitions of internal energy then no
Last edited by Meowstic; 6 days ago
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NonIndigenous
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(Original post by Meowstic)
It depends on what you are doing. In most cases you'd say no, it increases the energy stored in the gravitational field; but it's convention in thermodynamics to include all energies capable of doing work in the internal energy, so if you were doing a thermodynamical calculation then yes.
Surely though, the act of lifting the ice block alone doesn't increase its internal energy? Same way that its internal energy isn't increasing due to it traveling however many thousands of kilometers per second the Earth travels at through space.

If you're talking about overcoming its inertia on the other hand, that's slightly different. You could then raise its internal energy merely by applying force on it, without applying enough force to lift it in the first place. But that would be negligible anyway. In theory also, its internal energy would be raised merely by the equal and opposite reactions of the ice block simply sitting on the floor from the force of gravity.
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Meowstic
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(Original post by NonIndigenous)
Surely though, the act of lifting the ice block alone doesn't increase its internal energy? Same way that its internal energy isn't increasing due to it traveling however many thousands of kilometers per second the Earth travels at through space.

If you're talking about overcoming its inertia on the other hand, that's slightly different. You could then raise its internal energy merely by applying force on it, without applying enough force to lift it in the first place. But that would be negligible anyway. In theory also, its internal energy would be raised merely by the equal and opposite reactions of the ice block simply sitting on the floor from the force of gravity.
You are moving it in a gravitational potential.
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Stonebridge
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It's difficult to answer a vague question with a precise answer. But it's never stopped anyone trying.
My own thoughts, for what they are worth...
1. the answer you get will depend on what level you want to discus this at, and what background conditions you are applying to clarify what you mean here,
2. in physics we like to draw a nice distinction between potential energy (of the gravitational kind) and internal energy - so it would be very nice and convenient to answer 'no' to this question at the most basic and superficial level, but
3. isn't the test of whether you change the internal energy of the object the answer to whether you have either taken or removed any amount of 'heat' dQ and whether or not you have done any work dW on the object against the kinetic energies or molecular potential energies inside it.
4. as far as the heat is concerned we have no information in the question to be able to answer this - is it warmer or cooler at the top of the stairs, resulting in this movement causing a dQ - I don't think this was intended. Did the friction of the air moving over the surface as we moved it cause a rise in temperature? Again, I doubt this was intended. All speculation.
5. as far as work done dW, have we compressed or stretched the bonds inside the ice? Or more specifically, are they different at the top of the stairs from the bottom? We may have done a bit of compressing/stretching as we moved it, but was that change permanent?
6. work done against the gravitational field, by definition, increases only the gravitational potential energy of the block
7 work done against the internal forces and change to the kinetic energies of the molecules increases the internal energy

So the answer is...
Are we any the wiser.
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NonIndigenous
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(Original post by Stonebridge)
It's difficult to answer a vague question with a precise answer. But it's never stopped anyone trying.
My own thoughts, for what they are worth...
1. the answer you get will depend on what level you want to discus this at, and what background conditions you are applying to clarify what you mean here,
2. in physics we like to draw a nice distinction between potential energy (of the gravitational kind) and internal energy - so it would be very nice and convenient to answer 'no' to this question at the most basic and superficial level, but
3. isn't the test of whether you change the internal energy of the object the answer to whether you have either taken or removed any amount of 'heat' dQ and whether or not you have done any work dW on the object against the kinetic energies or molecular potential energies inside it.
4. as far as the heat is concerned we have no information in the question to be able to answer this - is it warmer or cooler at the top of the stairs, resulting in this movement causing a dQ - I don't think this was intended. Did the friction of the air moving over the surface as we moved it cause a rise in temperature? Again, I doubt this was intended. All speculation.
5. as far as work done dW, have we compressed or stretched the bonds inside the ice? Or more specifically, are they different at the top of the stairs from the bottom? We may have done a bit of compressing/stretching as we moved it, but was that change permanent?
6. work done against the gravitational field, by definition, increases only the gravitational potential energy of the block
7 work done against the internal forces and change to the kinetic energies of the molecules increases the internal energy

So the answer is...
Are we any the wiser.
You forgot to mention the effect which moving the block of ice would have on the Earth's center of mass (when considering the Earth and all objects on its surface as a closed system), and how it would affect the moon's orbit, and the Earth's orbit around the sun, and what further effects those may potentially have:
- shorter days?
- longer days?
- longer winters?

All that could effect the temperature, and maybe it's all we need to push us over the tipping point and trigger a climate catastrophe.
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jonnypdot
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No
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